U.  S.  DEPARTMENT  OF  AGRICULTURE, 
BUREAU  OF  ENTOMOLOGY — BULLETIN  No.  91. 

L.  O.  HOWARD.  Entomologist  and  Chief  of  Bureau. 


THE  IMPORTATION  INTO  THE  UNITED  STATES 
OF  THE  PARASITES  OF  THE  GIPSY  MOTH 
AND  THE  BROWN-TAIL  MOTH : 

A  REPORT  OF  PROGRESS,  WITH  SOME  CONSIDERATION  OF 
PREVIOUS  AND  CONCURRENT  EFFORTS  OF  THIS  KIND. 


L.  O.  HOWARD, 

Chief,  Bureau  of  Entomology, 

W.  F.  FISKE, 

In  Charge,  Gipsy  Moth  Parasite  Laboratory, 
Melrose  Highlands,  Muss. 


WASHINGTON  : 
GOVERNMENT  PRINTING  OFFICE. 
1911. 


Bui.  91,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agriculture. 


Plate  I. 


Calosoma  sycophanta. 


Adult  eating  gipsy-moth  caterpillar,  lower  left;  pupa,  lower  right;  eggs,  upper  left;  eaten  chrys- 
alides of  gipsy  moth,  upper  right;  full-grown  larvaj  from  above  and  from  below.  (Original.) 


U.  S.  DEPARTMENT  OF  AGRICULTURE, 
BUREAU  OF  ENTOMOLOGY— BULLETIN  No.  91. 

L.  O.  HOWARD,  En:omo!ogIsl  and  Chief  of  Bureau. 


THE  IMPORTATION  INTO  THE  UNITED  STATES 
OF  THE  PARASITES  OF  THE  OiPSY  MOTH 
AND  THE  BROWN-TAIL  MOTH: 

A   B BPORT  OF  PROGRESS,  WITB  SOME  CONSIDERATION  OF 
PSEYIOUS  LSD  CONCURRENT  EFFORTS  OF  THIS  KIND. 

BY 

L.  O.  HOWARD, 

Chief,  Bureau  cf  Entomology, 

AND 

W.  F.  FLSKE, 

In  Charge,  Gipsy  Moth  Parasite  Laboratory, 

Mebrace  Eijhlcmds,  Mass. 


rastJBD  July  29,  1911. 


WASHINGTON  : 
GOVERNMENT   PRINTING  OFFICE. 
ID'  1. 


B  UREA  U  OF  ENTOMOLOGY. 


L.  0.  Howard,  Entomologist  and  Chief  of  Bureau. 
C.  L.  Marlatt,  Entomologist  and  Acting  Chief  in  Absence  of  Chief. 
R.  S.  Clifton,  Executive  Assistant. 
W.  F.  Tastet,  Chief  Cleric. 

F.  H.  Chittenden,  in  charge  of  truck  crop  and  stored  product  insect  investigations. 

A.  D.  TTopkins,  in  charge  of  forest  insect  investigations. 

W.  D.  Hunter,  in  charge  of  southern  field  crop  insect  investigations. 

F.  M.  Webster,  in  charge  of  cereal  and  forage  insect  investigations. 

A.  L.  Quaintance,  in  charge  of  deciduous  fruit  insect  investigations. 

E.  F.  Phillips,  in  charge  of  bee  culture. 

D.  M.  Rogers,  in  charge  of  preventing  spread  of  moths,  field  work. 
Rolla  P.  Currie,  in  charge  of  editorial  work. 
Mabel  Colcord,  in  charge  of  library. 

Preventing  Spread  of  Moths. 

parasite  laboratory. 

W.  F.  Fiske,  in  charge;  A.  F.  Burgess,  C.  W.  Collins,  R.  Wooldridge,  J.  D. 
Tothill,  C.  W.  Stockwell,  H.  E.  Smith,  W.  N.  Dovener,  F.  II.  Mosher, 
assistants. 

field  work. 

D.  M.  Rogers,  in  charge;  H.  P>.  Dalton,  II.  W.  Vinton,  D.  G.  Murphy,  I.  L. 
Bailey,  H.  L.  McIntyre,  assistants. 

2 


LETTER  OF  TRANSMITTAL 


U.  S.  Department  of  Agbighltube, 

Bureau  of  Entomology, 
Washington,  P.  ('..  April  12.  1911. 

Sir:  I  have  the  honor  to  transmit  herewith  tin4  manuscript  of  a 
report  of  progress  on  the  importation  into  the  United  States  of  the 
parasites  of  the  gipsy  moth  and  the  brown-tail  moth.  To  this  has 
been  added  some  consideration  of  previous  and  concurrent  efforts  to 
handle  the  parasites  of  destructive  insects  in  a  practical  way.  The 
work  with  the  foreign  parasites  of  the  gipsy  moth  and  the  brown- 
tail  moth  lias  been  <roin^  on  now  for  rather  more  than  five  years. 
I:  promises  excellent  results,  and  the  present  seems  the  proper 
time  to  present  to  the  people  interested  a  somewhat  detailed  account 
of  what  has  been  done  and  of  the  present  condition  of  the  work.  \ 
recommend  that  this  manuscript  be  published  as  Bulletin  No.  91 
of  this  bureau. 

Respectfully,  I..  0.  Howard, 

I'lhttunnhujlst  ami  Chief  of  Bureau. 

I  [on,  James  Wilson, 

Secretary  of  Agriculture. 

3 


Digitized  by  the  Internet  Archive 
in  2013 


http://archive.org/details/impoOOunit 


COXT  F.NTS. 


Page. 


Introduction   13 

Previous  work  in  the  practical  handling  of  natural  enemies  of  injurious  insects. .  1G 

Early  practical  work   17 

Permitting  the  parasites  to  escape   18 

The  transportation  of  peraflitefl  from  one  part  of  a  iriven  country  to  another 

part   20 

The  transfer  of  beneficial  insects  from  one  country  to  another   23 

Early  attempts   23 

The  Australian  ladybird   (Aom/s  airdhmlis  Muls.)  in  the  United 

States   24 

Novius  in  Portugal     27 

Icerya  in  Florida   28 

Novius  in  Cape  Colony   28 

Novius  in  Egypt  and  the  Hawaiian  Island.-   28 

T?erya  in  Italy   29 

Icerya  in  Syria   29 

The  reasons  fur  the  success  of  Novius  •. . .  29 

Introduction  of  Entafon  <  ptyoni/s  W  alk,  into  the  United  States   30 

Other  introductions  by  Kocbele  into  California   31 

[nteroatkmal  work  with  enemies  of  the  Mack  scale   31 

The  Hawaiian  work   34 

An  importation  of  Clerufl  from  Germany   36 

MarlatCs  journe\  for  enemies  of  the  San  Jose  scale   36 

The  parasites  of  pia.spi.s  /»  nlatjona  Targ  -   38 

The  work  of  Mr.  (iconic  Compere   38 

Work  with  the  egg  parasite  of  the  elm  leaf  hectic   39 

Work  with  parasites  of  ticks   41 

Mr.  Froggatt's  journey  to  various  parts  of  the  world  in  1!»07-S   42 

Other  work  of  this  kind  (by  Iierlese;  by  Silvestri;  in  Algeria;  in  the 

Philippines;  by  De  Buasy;  in  Peru)   44 

Early  ideas  on  introducing  the  natural  enemies  of  the  gipsy  moth   47 

Circumstances  which  brought  about  the  actual  beginning  of  the  work   49 

An  investigation  ol  the  introduction  work   50 

Namtive  of  the  progress  of  the  work   54 

Known  and  recorded  parasites  of  the  gipsy  moth  and  of  the  brown-tail  moth. . .  84 

Establishment  and  dispersion  of  the  newly  introduced  parasites   94 

Disease  as  a  factor  in  the  natural  control  of  the  gipsy  moth  and  the  brown-tail 

moth   97 

Studies  in  the  parasitism  of  native  insects   102 

Parasitism  as  a  factor  in  insect  control   105 

The  rate  ol  increase  of  the.  gipsy  moth  in  New  England   109 

Amount  of  additional  control  necessary  to  check  the  increase  ol  the  gipsy  moth 

.  in  America   114 

The  extent  to  which  the  gipsy  moth  is  controlled  through  parasitism  abroad   117 

Parasitism  of  the  gipsy  moth  in  Japan   120 

Parasitism  ol  the  gipsy  moth  in  Russia   123 

Parasitism  of  the  gipsy  moth  in  southern  France   129 

5 


6  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

Page. 

Sequence  of  parasites  of  the  gipsy  moth  in  Europe   131 

The  brown-tail  moth  and  its  parasites  in  Europe   132 

Sequence  of  parasites  of  the  brown-tail  moth  in  Europe   135 

Parasitism  of  the  gipsy  moth  in  America   136 

Summary  of  rearing  work  carried  on  at  the  laboratory  in  1910   141 

Parasitism  of  the  brown-tail  moth  in  America   143 

Summary  of  rearing  work  in  1910   146 

Importation  and  handling  of  parasite  material   152 

Egg  masses  of  the  gipsy  moth   152 

Gipsy-moth  caterpillars,  first  stage   153 

Gipsy-moth  caterpillars,  second  to  fifth  stages  ,  154 

European  importations   154 

Japanese  importations   155 

Gipsy-moth  caterpillars,  full-fed  and  pupating   156 

Gipsy-moth  pupa1   159 

Brown-tail  moth  egg  masses   160 

Hibernating  nests  of  the  brown-tail  moth   161 

Immature  caterpillars  of  the  brown-tail  moth   161 

Full-fed  and  pupating  caterpillars  of  the  brown-tail  moth   162 

Brown-tail  moth  pupae   164 

Cocoons  of  hymenopterous  parasites   165 

Tachinid  puparia   166 

Calosoma  and  other  predaceous  beetles   167 

Quantity  of  parasite  material  imported   167 

Localities  from  which  the  parasite  material  has  been  received   168 

The  egg  parasites  of  the  gipsy  moth   168 

Anastatus  bifasciatus  Fonsc   168 

Schedius  kuvanoe  How   176 

Life  of  Schedius  and  its  relations  to  other  egg  parasites,  primary  and 

secondary   177 

Rearing  and  colonization   184 

The  parasites  of  the  gipsy-moth  caterpillars   188 

Apparently  unimportant  hymenopterous  parasites   188 

Apanteles  solitarius  Ratz   189 

Meteorus  versicolor  Wesm   190 

Meteorus  pulchricornis  Wesm   190 

Meteorus  japonicus  Ashm   190 

Limnerium  disparts  Vier   191 

Limnerium  (Anilastus)  tricoloripes  Vier   192 

Apanteles  fulvipes  Hal   193 

Secondary  parasites  attacking  Apardeles  fulvipes   198 

Tachinid  parasites  of  the  gipsy  moth   202 

The  rearing  and  colonization  of  tachinid  flies;  large  cages  versus  small  cages.  204 

Hyperparasites  attacking  the  Tachinidae   207 

Penlampus  cuprinus  Forst     208 

Melittobia  acasta  Walk   209 

Chalcis  fiskei  Crawf   212 

Monodon tomerus  xreus  Walk   212 

Miscellaneous  parasites   213 

Blcpharipa  scvtcflafa  Desv   213 

Com psilura  mucin nnta  Meig   218 

Tachina  larvarum  L   225 

Tachina  japonica  Towns   227 


CONTENTS.  7 

Tachinid  parasites  of  the  gipsy  moth— Continued.  Page. 

Ti  i,  h<>\  fga  grofu  is  Zett   228 

PatOM  /"/'  no  segregate  Bond   229 

CarceKa  gnetva  Meig   231 

Zggobotkria  nidicola  Towns   232 

Crossorostniii  aerieari*  Corn   232 

i  'roHHorosm  ia  flavoscutellata  Schiner  (?)   234 

Unimportant  tachinid  parasites  of  the  gipsy  moth   235 

Parasites  of  the  gipsy-moth  pupa3   236 

The  genus  Theronia     236 

The  genus  Pimpla                                                      .    237 

Irh/u  union  disparts  Poda   239 

The  genus  Chalcis   240 

MoiKximttoim  nis  i  rem  Walk   245 

The  sareophagids     250 

The  predaceotis  bootloB   251 

The  egg  parasites  of  the  brown-tail  moth   2"»6 

The  genus  Tri<  h<  >_rramma   256 

Telvnomuc  phahniarum  Nees   260 

Parasites  which  hibernate  within  tin*  webs  of  the  brown-tail  moth   261 

I'tdiculoides  ventricoaus  Xewp   267 

Pteromahu  egregius  Forst   268 

Apantehs  Inrtricolor  Vier   278 

Apantehs  conspersx  Fiske   285 

Meteorus  versicolor  Wesm   2S6 

Eygobotkria  nidicola  Towns   289 

Parasites  attacking  the  larger  can  rpillars  of  the  brown-tail  moth   295 

II\  menopterous  parasites   295 

Tachinid  parasites   296 

/>,  vedts  nigripes  Fall   296 

Parexorista  dbdonus  Rood   297 

Paks  pavida  Meig   300 

ZemUia  Matrix  Pan/.   302 

Masieera  syhatica  Fall                                                       ...    303 

Eudoromyiu  mngniroin is  Zett     303 

Cycloto phrys  a  user  Towns  :   304 

Blephnridea  vulgaris  Fall     304 

Parasite*  of  the  pupa*  of  the  brown-tad  moth   304 

Summary  and  conclusions   305 

The  present  status  of  the  introduced  parasites   307 

The  developments  of  the  year  1910   311 


i  1.1. 1  ST  RATIONS. 


PLATES. 


Page. 

I.  The  Calosoma  beetles   Frontispiece. 

II.  Fig.  1. — View  of  parasite  laboratory  at  North  Saugus,  Mass. 
Fig.  2. — View  of  parasite  laboratory  at  Melrose  Highlands, 
Mass   56 

III.  Fig.  1. — Roadside  oak  in  Brittany,  with  leaves  ragged  by 

gipsy-moth  caterpillars.  Fig.  2. — M.  Rene*  Oberthiir,  Dr. 
Paul  Marehal;  with  roadside  oaks  ragged  by  gipsy-moth 
caterpillars   76 

IV.  Fig.  I. — Caterpillar  hunters  in  the  south  of  France,  under  If. 

lMllon,  190;).    Fig.  2.  -Packing  parasitized  caterpillars  at 

Hvercs,  Franco,  for  shipment  to  the  I'nited  States,  1:109   76 

V.  Fig.  I.— -View  of  interior  of  one  of  the  laboratory  structures, 
showing  rearing  cages  for  brown-tail  moth  parasites.  Fig. 
2.  li"\  used  in  shipping  immature  caterpillars  of  the  gipsy 
moth  from  Japan   152 

VI.  The  gipsy  moth  (Poriketria  ditpar)   156 

VI  I.  The  brown-tail  moth  (  Eujtroctis  chri/s<>rrfoi  u  )   160 

VIII.  Fig.  I.  -  Boxes  used  in  l!)10  for  importation  of  brown-tail  moth 
caterpillars,  with  tubes  attached  directly  to  boxes.  Fig. 
2.— Interior  of  boxes  in  which  brown-tail  moth  caterpillars 
were  imported,  showing  condition  on  receipt.  Fig.  3. — 
Boxes  used  in  shipping  caterpillars  of  the  gipsy  and  brown- 
tail  moths  by  mail   164 

IX.  Fig.  1.  —  Headgear  devised  by  Mr.  B.  S.G.  Titus  as  a  protection 
against  brown-tail  rash.  Fig.  2.  Show  case  used  when 
opening  boxes  of  brown-tail  moth  caterpillars  received  from 

abroad   164 

X.  Fig.  1.  — Large  tube  cage  first  used  t'<»r  rearing  parasites  from 
imported  brown-tail  moth  nests  and  latterly  for  various  pur- 
poses.   Fig.  2. — Method  of  packing  Calosoma  beetles  for 

shipment   164 

XI.  Fig.  1. — Egg  of  gipsy  nvnh  containing  developing  caterpillar 
of  the  gipsy  moth.  Fi_r.  2.-  Egg  of  gipsy  moth,  containing 
larva  of  the  parasite  A  astatus  bi/a8ci:tus.  Fig.  3.— Egg  of 
gipsy  moth,  containing  hibernating  larva  of  Anustatus  bi/us- 
ciutus  which  in  turn  is  parasitized  by  three  second-stage 
larva?  of  Schedius  kuvanse   172 

XII.  Fig.  1.— View  of  cage  used  for  colonization  of  Anustatus  bi/us- 
ciatus  in  1910.  Fig.  2. — Views  of  cage  prepared  for  use  in 
colonization  of  Anustatus  bi/asciatus  in  1911   172 

XIII.  Outdoor  parasite  cage  covered  with  wire  gauze   204 

XIV.  Outdoor  parasite  cages  covered  with  cloth   204 

XV.  View  oi  large  cage  used  in  1908  for  tachinid  rearing  work   204 

9 


10 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


.Tage. 

Plate      XVI.  View  of  out-of-door  insectary  used  for  rearing  predaceous 


beetles  in  1910   204 

XVII.  Fig.  1. — Wire-screen  cages  used  in  tachinid  reproduction  work 
in  1909.    Fig.  2. — Cylindrical  wire-screen  cages  used  in 

**- tachinid  reproduction  work  in  1910    204 

XVIII.  Fig.  1. — Blepharipa  scutellata:  Full-grown  larva  from  gipsy- 
moth  pupa.    Fig.  2. — Blepharipa  scutellata:  Puparia   216 

XIX.  Fig.  1. — Importation  of  gipsy-moth  caterpillars  from  France  in 
1909;  en  route  to  laboratory  at  Melrose  Highlands,  Mass. 
Fig.  2. — Importation  of  gipsy-moth  caterpillars  from  France 

in  1909;  receipt  at  laboratory,  Melrose  Highlands,  Mass   216 

XX.  Fig.  1. — Compsilura  concinnata:  Puparia.    Fig.  2. — Tachina 
larvarum:  Puparia.    Fig.  3. — Sarcophaga  sp.:  Puparia.  Fig. 

4. — Parexoristacheloni.de:  Puparia   220 

XXI.  Fig.  1.— View  of  laboratory  interior,  showing  cages  in  use  for 
rearing  parasites  from  hibernating  webs  of  the  brown-tail 
moth  in  1910-11.    Fig.  2. — Sifting  gipsy-moth  egg  masses 

for  examination  as  to  percentage  of  parasitism   244 

XXII.  Map  showing  sections  of  its  range  in  New  England  from  which 
Monodontomerus  sereus  has  been  collected  in  hibernating 

webs  of  the  brown-tail  moth,  and  subsequently  reared   248 

XXIII.  Map  showing  distribution  of  Monodontomerus  sereus  in  New 

England   248 

XXIV.  Map  showing  dispersion  of  Calosoma  sycophanta  in  Massachu- 
setts from  liberated  colonies   256 

XXV.  Map  showing  distribution  of  Pteromalus  egregius  in  New 

England   276 

XXVI.  Fig.  1. — Riley  rearing  cages  as  used  at  the  gipsy-moth  parasite 
laboratory.  Fig.  2. — Interior  of  one  of  the  laboratory  struc- 
tures, showing  trays  used  in  rearing  Apanteles  lacteicolor  in 

the  spring  of  1909   280 

XXVII.  View  of  laboratory  interior,  showing  cages  in  use  for  rearing 
parasites  from  hibernating  webs  of  the  brown-tail  moth  in 

the  spring  of  1908   280 

XXVIII.  Fig.  1.— Cocoons  of  Apanteles  lacteicolor  in  molting  webs  of  the 
brown-tail  moth.  Fig.  2. — View  of  laboratory  yard,  showing 
various  temporary  structures,  rearing  cages,  etc   284 

TEXT  FIGURES. 

Fig.  1.  Polygnotus  hiemalis,  a  parasite  of  the  Hessian  fly   21 

2.  Polygnotus  hiemalis:  Adults  which  have  developed  within  the  "flax- 

seed" of  the  Hessian  fly  and  are  ready  to  emerge   21 

3.  Lysiphlebus  tritici  attacking  a  grain  aphis   22 

4.  The  Australian  ladybird  (Novius  cardinalis),  an  imported  enemy  of  the 

Huicd  scale:  Larvae,  pupa,  adult,  work  against  scales   23 

5.  Rhizobius  ventralis,  an  imported  enemy  of  the  black  scale:  Adult ,  larva .  31 

6.  Scutellista  cyanea,  an  imported  parasite  of  the  black  scale   32 

7.  I'rdiculoidrs  rentricosus   34 

8.  Krastria  sritula,  an  imported  enemy  of  the  black  scale:  Adult,  larva?, 

pupa   34 

9.  The  Asiatic  ladybird  ( Chilocorus  si  mil  is),  an  imported  enemy  of  the  Sail 

Jose  scale:  Later  larval  stages,  pupa,  adults   37 

L0.  Hearing  cage  !'<»r  tachinid  parasites  of  the  brown-tail  moth   151 


ILLUSTRATIONS.  1  ] 

Pa-je. 

Fig.  11.  Map  showing  various  localities  in  Europe  from  which  parasite  material 

has  been  received   .  169 

12   Anastatus  bifasciatus:  Adult  female   170 

13.  Anastatus  bifasciatus:  Uterine  egg   171 

14.  Anastntusbifasciatus:  Hibernating  larva   171 

15.  Anastatus  bifasciatus:  Pupa  from  gipsy-moth  egg   171 

16.  Diagram  showing  two  years'  dispersion  of  Anastatus  bifasciatus  from 

colony  center   173 

17.  Schedius  kuvanse:  Adult  female   176 

18.  Schedius  kurame:  Egg.  ,   179 

19.  Srhcdius  kuranir:  Third-stage  larva  still  retaining  attachment  to  egg 

stalk,  and  anal  shield   180 

20.  Schrdius  kuvanx:  Pupa   180 

21.  Schedius  kuranu:  Egg  stalk  and  anal  shield  of  larva  as  found  in  host 

eggs  of  gipsy  moth  from  which  t ho  adult  Schedius  has  emerged,  <>;■  in 

which  the  Schedius  larva  has  been  attacked  by  a  secondary  parasite.  181 

22.  Schrdius  kuranx:  Larval  mandibles   181 

23.  Tundarichus  navx:  Larval  mandibles   181 

24.  Pachyneuron  gifuensis:  Egg   182 

25.  Pachyneuron  gifuensis:  Larval  mandibles   182 

26.  Anastatus  bifasciatus:  Larval  mandibles   182 

27.  Gipsy-moth  egg  mass  showing  exit  holes  of  Schedius  lur<:n;i   186 

28.  Apantales  tolUeriuM:  Adult  female  and  cocoon   189 

29.  Limnrrium  disparis:  Cocoon   191 

30.  Li  unit  riu  111  disparis:  Adult  male   191 

31.  Apanteles  fulripes:  Adult   193 

32.  Apanteles  fulripis:  Larva*  leaving  gipsy-ninth  caterpillar   If)} 

33.  Apanteles  fulripes:  ( 'ocoons  surrounding  dead  gipsy-moth  caterpillar.  195 

34.  Apanteles  fulripes:  Cocoons  from  which  Apanteles  and  its  secondaries 

have  issued   199 

35.  Blepharipa  scutdlata:  Adult  female   213 

36.  Blepharipa  scutdlata:  Eggs  in  situ  on  fragment  of  leaf   214 

37.  Eggs  of  Blepharipa  scutdlata  and  Pules  parii.'a   214 

58.  Blepharipa  srutellata:  First -stage  larva*   215 

3D.  Blepharipa  scutdlata:  Second-stage  larva  in  situ   215 

40.  Blepharipa  scutdlata:  Nasal  port  ion  of  tracheal  "funnel"   216 

41.  Compsilura  cn/iciniiuta:  Adult  female  and  details   219 

42.  Map  showing  distribution  of  CompsUura  eoncinnata  in  Massachusetts.  222 

43.  Taehina  larraruin:  Adult  female  and  head  in  profile   225 

4\  Chalcis  Jlaripes:  Adult   241 

45.  Chalcis jlavipes,  female:  Hind  femur  and  tibia,  showing  markings...  212 

•1  ;.  Chalcis  ohsenruta.  female:  Hind  femur  and  tibia,  showing  markings.  .  242 

47.  Chalcis jlarlp,  .<:  Full-grown  larva  from  gipsy-moth  pupa   243 

48.  Chalcis  Jlaripes:  Pupa,  side  view   243 

49.  Chalcis  Jlaripes:  Pupa,  ventral  view   243 

50.  Gipsy-moth  pupa?,  showing  exit  holes  of  ChaL  \tfiax  ipes   243 

51.  Monodontomerus  u  reus:  Adult  female   244 

52.  Monodontomerus  aereus:  Egg   249 

53.  Monodontomerus  ,i  reus:  Larva   249 

64.  Monodontomerus  ;rreus:  Pupa,  side  view   249 

55.  Monodontomerus  areus:  Pupa,  ventral  view..   249 

56.  Gipsy-moth  pupa  showing  exit  hole  left  by  Monodontomerus  aereus   250 

57.  Trichogramma  sp.  in  act  of  oviposition  in  an  egg  of  the  brown-tail  moth.  256 


12 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Page. 


Fig.  58.  Eggs  of  the  brown-tail  moth,  a  portion  of  which  has  been  parasitized 

by  Trichogramma  sp   257 

59.  Larvae  of  Pleromalus  egregius  feeding  on  hibernating  caterpillars  of 

the  brown-tail  moth   262 

60.  Portion  of  brown-tail  moth  nests,  torn  open,  showing  caterpillars 

attacked  by  larvae  of  Pteromalus  egregius   263 

61.  Apanteles  lacteicolor:  Immature  larva  from  hibernating  caterpillar  of 

the  brown-tail  moth   263 

62.  Meteorus  versicolor:  Immature  larva  from  hibernating  caterpillar  of 

the  brown-tail  moth   284 

63.  Zygobothria  nidicola:  First-stage  larvae  in  situ  in  walls  of  crop  of  hiber- 

nating brown-tail  moth  caterpillar   264 

64.  Compsilura  concinnata:  First-stage  larva   265 

65.  Pteromalus  egregius:  Adult  female   269 

66.  Pteromalus  egregius:  Female  in  the  act  of  oviposition  through  the  silken 

envelope  containing  hibernating  caterpillars  of  the  brown-tail  moth.  274 

67.  Apanteles  lacteicolor:  Adult  female  and  cocoon   279 

68.  Meteorus  versicolor:  Adult  female  and  cocoons   287 

69.  Zygobothria  nidicola:  Adult  female  and  details   290 

70.  Pales  pavida:  Adult  female  and  details   331 

71.  Pales  pavida:  Second-stage  larva  in  situ  in  basal  portion  of  integu- 

mental  ' 'funnel"   302 

72.  Pales  pavida:  Integumental  "funnel,"  showing  orifice  in  skin  of  host 

caterpillar   302 

73.  Eudoromyia  magnicornis:  Adult  female  and  details   303 

74.  Eudoromyia  magnicornis:  First-stage  maggot  and  mouth  hook   333 


THE  IMPORTATION  INTO  THE  UNITED  STATES  OE  THE 
PARASITES  OF  THE  GIPSY  MOTH  AND  THE  BROWN- 
TAIL  MOTH: 

A  REPORT  OF  PROGRESS, 

W  ith  Somk  < 'o\sidf.ratio\  of  Previous  and  Com  tkkknt  Efforts  of  this  Kind. 


INTRODUCTION. 

By  L.  0.  Howard, 
Chief i  Hunan  of  Entomology. 

As  will  appeal  from  the  opening  portion  of  this  bulletin,  which 
gives  an  account  of  previous  work  in  tin*  practical  handling  of  natural 
enemies,  carried  on  in  various  parts  of  the  world,  nothing  comparable 
to  the  work  which  is  to  be  described  has  ever  before  been  undertaken. 
As  will  appear  also,  most  of  the  successful  work  in  this  direction  has 
been  done  with  the  faced  scale  insects.  The  exceptions  to  this  gen- 
eral statement  among  the  measurably  successful  efforts  have  been  the 

introduction  of  parasites  of  the  sugar-cane  leafhopper  into  Hawaii, 
some  reported  work  in  the  introduction  of  South  American  natural 
enemies  of  fruit  Hies  into  Western  Australia,  and  the  introduction  of 
one  of  the  many  European  enemies  of  the  codling  moth  from  Spain 
into  California;  but  it  does  not  appear  that  practical  results  of  anj 
very  great  value  have  been  achieved  by  the  la^t  two  introductions, 
although  information  from  Western  Australia  is  scanty.  At  the 
time  when  the  work  began  nothing  practical  had  been  accomplished 
witli  the  natural  enemies  of  any  Lepidopterous  insects,  and  in  the  whole 
history  of  the  practical  handling  of  parasites  no  work  of  this  character 
has  ever  been  attempted  upon  anything  like  the  large  scale  with 
which  the  present  work  lias  been  carried  on.  Some  studies  had  already 
been  made  both  by  the  writer  and  by  Mr.  Fiske  on  the  subject  of  the 
intensive  parasitism  of  two  native  species  of  American  moths,  and 
for  years  the  bureau  had  been  keeping  records  of  the  roarings  of 
parasites  of  lepidopterous  inse  ts  as  well  as  of  others;  moreover,  the 
writer  had  made  a  careful  study  of  the  records  of  the  rearings  of 
hymenopterous  parasites  from  host  insects  all  over  the  world  and 
had  accumulated  an  enormous  catalogue  of  such  records.  Never- 
theless the  initial  work  on  such  a  scale  was  experimental  in  its  charac- 
ter,  It  seemed  to  the  writer  that  by  attempting  to  reproduce  in  Xew 

13 


14 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


England  as  nearly  as  possible  the  entire  natural  environment  of  the 
gipsy  moth  and  the  brown-tail 'moth  in  their  native  homes,  similar 
conditions  of  comparative  scarcity  could  surely  be  reached,  and  this 
view  he  still  holds  with  enthusiasm.  Naturally,  in  the  course  of  the 
work  as  it  progressed  year  after  year  his  ideas  have  been  changed  as 
to  methods,  and  very  great  improvements  have  been  made  upon  the 
earlier  methods,  largely  through  the  intelligence  and  ingenuity  of 
the  junior  author  of  this  bulletin.  Moreover,  the  careful,  intensive 
studies  which  have  been  made  at  the  gipsy-moth  parasite  laboratory 
by  the  junior  author  and  a  corps  of  trained  assistants,  aided  by 
abundant  material,  funds,  and  supplies,  have  resulted  not  only  in  the 
ascertainment  of  very  many  facts  new  to  science,  but  in  the  accumu- 
lation of  such  facts  to  such  a  degree  as  to  enable  generalizations  of  a 
novel  character  and  of  a  sounder  basis  than  could  have  been  had 
under  other  conditions.  Many  points  are  brought  out  in  this  bulletin 
which  will  doubtless  be  entirely  new  to  the  trained  scientific  reader. 
Mistakes  have  been  made  and  wrong  conclusions  have  been  drawn 
from  time  to  time,  but  these  have  been  corrected,  and  we  are  now  in 
a  fair  way  to  see  a  favorable  result  from  the  long  and  expensive  work. 

The  initial  idea  was  that  since  a  large  percentage  of  gipsy-moth 
caterpillars  or  brown-tail  moth  caterpillars  in  Europe  contains  para- 
sites each  year,  therefore  if  these  caterpillars  were  brought  to  America 
in  large  numbers  from  every  possible  place  we  could  not  fail  to  rear 
from  them  an  abundance  of  adult  foreign  parasites.  This  idea  was 
sound,  and  in  following  it  out  we  have  constantly  improved  the 
methods — methods  of  collection,  of  packing,  of  shipment,  and  of 
subsequent  rearing.  Very  large  numbers  of  parasites  have  been 
reared. 

It  was  first  thought  that  when  parasites  had  been  reared  in  suffi- 
cient numbers  they  should  be  widely  distributed  in  small  colonies,  on 
the  theory  that  each  colony  would  remain  in  substantially  the  same 
general  locality  and  would  increase  and  spread  from  that  point.  This 
idea  was  a  natural  one  and  was  fully  justified  by  previous  work  which 
had  been  done  with  parasites  of  other  groups  of  insects,  but  in  this 
case  it  proved  to  be  erroneous,  and  valuable  time  and  valuable  speci- 
mens were  lost.  Eventually  it  was  shown  to  be  of  prime  importance, 
first  to  establish  a  given  species  of  parasite  in  this  country,  and  not 
until  this  lias  been  accomplished  to  pay  any  attention  to  the  matter 
of  dispersion.  It  seems  to  be  the  first  instinct  of  many  species  that 
have  been  imported  to  spread  widely.  Therefore,  if  the  colony  put 
out  be  a  small  one  the  individuals  composing  it  spread  rapidly 
beyond  nil  means  of  meeting  arid  of  mating,  and  thus  the  colonies  in 
man;,  instances  were  lost.  By  rearing  in  the  laboratory,  however^ 
until  colonies  of  at  least  a  thousand  are  to  be  had,  such  colonies 


INTRODUCTION. 


15 


while  dispersing  are  much  more  likely  to  remain  in  touch,  mate,  and 
multiply. 

By  methods  based  upon  the  first  idea,  and  by  the  subsequent  modi- 
fication of  the  second  idea,  some  of  the  most  important  natural  ene- 
mies of  both  species  have  been  established  in  the  United  States  to  a 
certainty.  It  has  been  found  with  several  species  that  they  could  not 
be  recovered  until  after  three  years  had  elapsed  from  the  time  of  the 
original  colonization;  hence  it  follows  with  a  reasonable  certainty 
that  other  species  which  have  not  been  recovered  will  ultimately  be 
recovered  as  a  result  of  colonization  one,  two,  and  three,  and  even 
perhaps  four  years  ago.  It  is  deemed,  however,  at  this  time  that 
nearly  as  much  has  been  accomplished  as  can  be  accomplished  by  the 
earlier  methods,  and  subsequent  efforts  will  be  devoted  to  a  more 
specific  attempt  to  import  the  species  still  Lacking,  several  of  which 
are  known  in  their  original  homes  to  hoof  very  great  importance.  As 
will  be  pointed  out  elsewhere,  attempts  will  also  be  made  to  import  the 
species  which,  while  of  Lesser  importance  ;it  home,  may  here  fill  in 
gaps  and  may  possibly  multiply  to  an  unprecedented  extent  in  the 
face  of  new  conditions  and  a  superabundance  of  host  material. 

The  work  has  been  going  on  since  L905.  Nothing  has  been  p  b- 
lished  concerning  its  progress  except  the  short  accounts  in  the  annual 
reports  of  the  writer  submitted  each  year  to  the  Secretary  of  Agri- 
culture, and  except  a  bulletin  on  the  general  subject  prepared  by  the 
junior  author  and  published  by  the  State  forester  of  Massachusetts. 
It  is  hoped  that  the  present  account  will  be  deemed  a  satisfactory 
reply  to  all  expressed  desire  for  information  as  to  progress. 

The  joint  authorship  of  the  bulletin  is  deemed  desirable  by  both 
authors,  but  the  writer  takes  it  upon  himself  to  sign  this  introduction 
for  the  explicit  purpose  of  stating  in  his  own  way  the  conditions  under 
which  it  has  been  prepared.  The  work  from  the  beginning  has  been 
under  the  direct  supervision  of  the  writer,  and  he  is  therefore  to  be 
held  responsible  for  any  failures  in  the  speedy  accomplishment  of 
results,  but  the  greatest  credit  in  bringing  about  the  results  which 
have  been  accomplished,  he  wishes  frankly  to  state,  belongs  to  Mr. 
Fiske.  Following  the  breakdow  n  in  health  of  Mr.  E.  S.  G.  Titus  in 
the  spring  of  1907,  as  is  shown  in  the  bulletin,  Mr.  Fiske  was  stationed 
at  the  parasite  Laboratory  and  has  since  been  given  every  freedom  in 
the  conduct  of  its  affairs.  Nearly  every  suggestion  which  lie  lias 
made,  while  it  has  been  fully  discussed  by  the  two  of  us,  has  been 
adopted.  The  ingenuity  which  he  has  displayed  in  matters  of  method 
and  the  broad  grasp  which  lie  lias  shown  of  tin4  whole  phenomena  of 
parasitism  in  insects,  together  with  his  competent  and  practical 
grouping  of  his  ideas,  deserve  every  praise.  Such  portions  of  the 
bulletin  as  were  dictated  by  the  writer  have  received  the  editorial 
criticism  of  the  junior  author,  and  the  portions  prepared  by  the  latter 


16 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


have  received  a  most  careful  consideration  and  editorial  priming  of 
the  writer.  Mr.  Fiske,  by  virtue  of  his  practical  residence  at  the  field 
laboratory  and  of  his  intimate  charge  of  all  the  field  notes  and  labo- 
ratory notes,  has  prepared  all  of  the  matter  in  this  bulletin  relating  to 
the  laboratory  and  field  end,  subject,  of  course,  to  the  writer's  revision. 
The  rest  has  been  prepared  by  the  senior  author. 

Acknowledgements  of  assistance  should  be  made  by  the  score.  The 
State  authorities  of  Massachusetts,  the  admirable  corps  of  laboratory 
and  field  assistants,  and  above  all  the  very  numerous  foreign  officials, 
voluntary  assistants,  and  paid  observers  have  united  to  make  the 
undertaking  possible.  Their  individual  names  are  all  mentioned  in 
the  following  pages  in  connection  with  the  parts  they  played,  but  the 
Governments  of  Austria,  France,  Germany,  Hungary,  Italy,  Japan, 
Portugal,  Russia,  and  Spain  should  especially  be  thanked  in  an  official 
publication  like  this  for  the  assistance  given  by  the  officials  of  these 
Governments. 

PREVIOUS  WORK  IN  THE  PRACTICAL  HANDLING  OF  NATURAL 
ENEMIES  OF  INJURIOUS  INSECTS. 

Two  very  thorough  and  careful  general  papers  on  the  subject  of  the 
practical  handling  of  natural  enemies  of  insects,  treating  the  subje<  t 
from  the  different  points  of  view,  including  the  historical  side,  have 
been  published  in  the  last  few  years.  The  first  of  these,  entitled  '  ■  The 
Utilization  of  Auxiliary  Entomophagous  Insects  in  the  Struggle 
against  Insects  Injurious  to  Agriculture,"  by  Prof.  Paul  Marchal,  of  the 
National  Agronomical  Institute  of  Paris,  was  published  in  1907,1  and 
was  partly  republished  in  English  in  the  Popular  Science  Monthly  in 
1908.2  The  other,  by  Prof .  F.  Silvestri,  of  the  Royal  Agricultural  School 
at  Portici,  Italy,  entitled  "  Consideration  of  the  Existing  Condition  of 
Agricultural  Entomology  in  the  United  States  of  North  America,  and 
Suggestions  which  can  be  Gained  from  it  for  the  Benefit  of  Italian 
Agriculture,"  was  published  in  1909.?  This  paper  was  in  part  trans- 
lated into  English  and  published  in  the  Hawaiian  Forester  and  Agri-  . 
culturist  for  August,  1909.  Both  of  these  papers  should  be  consulted 
by  persons  wishing  to  inform  themselves  thoroughly  on  this  question. 
For  the  present  purpose,  treatment  of  the  subject  must  be  brief. 

The  study  of  parasitic  and  predatory  insects  is  old.  Silvestri  has 
pointed  out  that  Aldrovandi  (1602)  was  the  first  to  observe  the  exit  of 
i  larvae  of  Apauteles  glomeratus  L.  (which  he  supposed  to  be  eggs) 
from  the  common  cabbage  caterpillar,  and  that  Kedi  (166S)  pub- 
lished the  same  observation  and  another  on  insects  of  different 
spe<  L  -  born  from  the  same  pupa.    A  later  writer,  Vallisnieri  (1661- 

1  knnali  of  the  National  Agronomii  ii  Institute  'Superior  School  of  Agriculture),  seoond  scries  vol.  6,  no. 
2,  pp.  2Sl-'j.j4,  Pari*,  l'J07. 

I'oj.iiI  ir  S<  ienre  Monthly,  \ol.  72,  pp.  .r>  t  {70.  4<)7  4H,  April  and  May,  19()<S. 

i  Bon  Hi  erf  •  t  to  ii-iv  of  [taMao  Agriculturlits,  vol.  u,  no.  8,  pp.  805-807)  Apr.  30, 1909. 


PREVIOUS  WORK   WITH  INSECT  PARASITES. 


17 


1730)  was  apparently  the  first  to  discover  the  real  nature  of  this  phe- 
nomenon and  to  realize  the  existence  of  true  parasitic  insects.  Reau- 
mur (1683-1757)  and  De  Geer  (1720-1778)  each  studied  the  life  his- 
tories of  living  insects  with  great  care  and  among  these  worked  out 
the  biology  of  a  number  of  parasites.  Very  many  descriptive  works 
on  parasites  were  published  in  the  closing  years  of  the  eighteenth 
century  and  the  beginning  of  the  nineteenth  century,  especially  by 
Dalman  (1778-1828),  Xees  ab  Esenbeck  (1776-1858),  Gravenhorst 
(1777-1857),  Walker  (publishing  from  1S33  to  1861),  Westwood 
(publishing  from  1827  on  through  nearly  the  whole  of  the  century), 
Forster  (publishing  from  1841  on),  and  Spinola  (1780-1857). 

Many  later  writers  have  contributed  to  the  systematic  study  of 
these  insects,  among  them  Holmgren  and  Thomson,  of  Sweden; 
Mayr,  of  Austria;  Motschulsky,  of  Russia;  Ratzeburg,  Ilartig,  and 
Schmiedeknecht,  of  Germany;  Wesmael,  of  Belgium;  Ilaliday, 
Marshall,  and  Cameron,  of  England;  Rondani,  of  Italy;  Brulle, 
Giraud,  Decaux,  and  others  in  France;  Provancher,  of  Canada;  and, 
in  America.  Cresson,  Riley.  Howard.  A-lmiead.  Crawford.  Yicrcck, 

Brues,  Girault,  and  othere. 

The  best  contribution  appearing  in  Europe  and  devoted  to  the 
biology  of  hymenopterons  parasites  and  especially  con>ideration  of 
their  relations  to  their  ho>t<.  was  that  by  Ratzeburg,  whose  great 
work  entitled  "Die  Ichneumonen  der  Forstinsekten, ' '  was  a  standard 
for  many  years.  Ratzeburg  understood  the  role  played  by  parasites 
in  the  control  of  forest  insects,  but  did  not  believe  that  this  control 
could  in  any  way  be  facilitated  by  man. 

EARLY  PRACTICAL  WORE 

Froggatt  has  pointed  out  that  probably  the  earliest  suggestion 
made  regarding  the  artificial  handling  of  beneficial  insects  1  as  printed 
in  Kirby  and  Spence's  entomology  ( 1 S 1  <> ) ,  where  the  authors  called 
attention  to  the  value  of  the  common  English  ladybird  as  destroying 
the  hop  aphis  in  the  south  of  England.  "If  we  could  but  discover  a 
mode  of  increasing  these  insects  at  will,  we  might  not  only  clear  our  hot- 
houses of  aphides  by  their  means,  but  render  our  crops  of  hops  much 
more  certain  than  they  are  now."  As  a  matter  of  fact,  gardeners 
and  florists  in  England  for  very  many  years  have  recognized  the  value 
of  the  ladybirds  and  have  transferred  them  from  one  plat  to  another. 

Prof.  A.  Trotter,  of  the  Royal  School  of  Viticulture  at  Avellino, 
Italy,  has  recently  pointed  out  in  an  interesting  paper  entitled  ''Two 
Precursors  in  the  Application  of  Carnivorous  Insects,"  published  in 
Redia,  in  1908. 1  that  probably  the  first  person  to  make  a  practical 
application  of  the  natural  enemies  of  injurious  species  was  Prof. 


i  Redia,  vol.  5,  pp.  120-132,  Florence,  1908. 
05077°— Bull.  91—11  '2 


18  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

Boisgiraud,  Of  Poitiers,  France,  in  1840.  Prof.  Trotter  found  this 
reference  in  a  little-known  paper  by  N.  Joly,  published  in  1842,  and 
entitled  "Xotice  of  the  Ravages  which  Liparis  dispar  L.  has  made 
around  Toulouse,  followed  by  some  Reflexions  upon  a  Method  of 
Destroying  Certain  Insects."  It  seems  that  Boisgiraud,  about  1840, 
freed  the  poplars  along  a  road  near  Poitiers  of  the  gipsy  moth  by 
placing  upon  them  the  carabid  beetle  Calosoma  sycophanta  L.,  and 
destroyed  earwigs  in  his  own  garden  by  placing  with  them  a  rove 
beetle  (Staphylinus  olens  Mull).  He  also  experimented  against  the 
same  insect  with  the  ground  beetle  Carabus  auratus  L.  His  experi- 
ment must  have  become  rather  well  known  at  the  time,  since  Prof. 
Trotter  points  out  that  in  1843  the  technical  commission  of  the 
Society  for  the  Encouragement  of  Arts  and  Crafts  of  Milan  offered  a 
gold  medal  to  be  given  in  1845  to  the  person  who  in  the  meantime 
should  have  undertaken  with  some  success  new  experiments  tending  to 
promote  the  artificial  development  of  some  species  of  carnivorous 
insects  which  could  be  used  efficaciously  to  destroy  another  species  of 
insect  recognized  as  injurious  to  agriculture.  This  offer  drew  forth  a 
memoir  from  Antonio  Villa,  a  well-known  writer  on  entomology,  who 
had  previously  confined  himself  to  the  Coleoptera,  entitled  "The  Car- 
nivorous Insects  used  to  Destroy  the  Species  Injurious  to  Agricul- 
ture." This  memoir  was  presented  December  26,  1844,  and  he  advo- 
cated the  emplo}^ment  of  climbing  carabid  beetles  for  tree-inhabiting 
forms,  rove  beetles  to  destroy  the  insects  found  in  flowers,  and  ground 
beetles  for  cutworms  and  other  earth-inhabiting  forms..  The  paper 
of  Villa  was  praised  in  certain  reviews  and  criticized  in  others.  It 
seems  to  have  been  entirely  lost  sight  of  in  later  years. 

A  later  Italian  writer,  Rondani,  who  devoted  himself  for  the  most 
part  to  systematic  work,  appreciated  the  practical  importance  of 
parasite  work  and  published  tables  giving  the  host  relations  of  differ- 
ent species.  His  work  influenced  many  arguments  in  the  dispute 
which  sprang  up  in  Italy  about  1868  as  to  the  usefulness  of  insec- 
tivorous birds  to  agriculture,  and  Silvestri  calls  attention  to  the  fact 
that  Dr.  T.  Bellenghi  was  referring  to  Rondani  when,  in  1872,  he  spoke 
what  Silvestri  calls  "the  prophetic  words:"  "Entomological  para- 
sitism has  a  future,  and  in  it  more  than  in  anything  else  Italian  agri- 
culture must  put  its  faith." 

PERMITTING  THE  PARASITES  TO  ESCAPE. 

The  earliest  published  suggestion  as  to  the  practical  use  of  para- 
sites of  injurious  insects,  by  permitting  the  parasites  to  escape  while 
the  host  insert  is  killed,  appears  to  have  been  made  by  C.  V.  Riley 
when  Slate  entomologist  of  Missouri.  Writing  of  the  rascal  leaf- 
crumpler  (  Mi  avoid  indiginella  Zell.)  in  his  Fourth  Report  on  the 


PREVIOUS  WORK  WITH  INSECT  PARASITES. 


19 


Insects  of  Missouri,1  he  advocated  the  collecting  of  the  winter  cases  of 
the  destructive  insect  and  placing  the  cases  in  small  vessels  in  the 
center  of  a  meadow  or  field,  away  from  any  fruit  trees,  with  the  idea 
that  the  worms  would  he  able  to  wander  only  a  few  yards  and  would 
perish  from  exhaustion  or  starvation,  while  their  parasites  would 
escape  and  fly  hack  to  the  fruit  trees.  It  is  stated  that  this  method 
was  put  in  practice  later  by  D.  B.  Wier  with  success. 

A  French  writer,  F.  Decaux,  the  following  year  made  practically 
the  same  suggestion  witJi  regard  to  apple  buds  attacked  by  Anthono- 
mus.  He  advised  that  instead  of  burning  these  .buds,  as  was  gener- 
ally done,  they  be  preserved  in  boxes  covered  with  gauze,  raising  the 
latter  from  time  to  time  during  the  period  of  issuing  of  parasites  so  as 
to  permit  them  to  escape.  In  1SS0  he  put  this  method  in  practice, 
and  collected  in  Picardy  buds  reddened  by  the  Anthonomus  from 
800  apple  trees,  and  thus  accomplished  the  destruction  of  more  than 
1,000, 000  individuals  of  the  Anthonomus,  setting  at  liberty  about 
250,000  parasites  which  aided  the  following  year  in  the  destruction  of 
the  weevils.  The  following  year  the  same  process  was  repeated,  and, 
the  orchards  being  isolated  in  the  middle  of  cultivated  I 'adds,  all  serious 
damage  from  the  Anthonomus  was  stated  to  have  been  stopped  for 
10  years.-' 

Practically  the  same  suggestion  was  made  later,  in  1S77,  by  J.  II. 
Comstoek,  in  regard  t<>  the  imported  cabbage  worm  (Poutia  ra />;r,  L.). 
Oomstock  deprecated  the  ^discriminate  crashing  of  the  chiysalids 
collected  under  trap  boards,  on  account  of  the  large  percentage  which 
contained  parasites.  He  recommended  instead  the  collecting  of  the 
chrysalids'and  placing  them  in  a  box  covered  with  a  wire  screen  which 
should  permit  the  parasites  to  escape  and  at  the  same  time  confine  the 
butterflies  so  that  they  could  be  easily  destroyed.  The  same  author, 
in  his  report  upon  cotton  insects/1  recommended  a  similar  course  with 
the  pupa*  of  t  he  cot  ton  caterpillar  (Alabama  argUlacea  Iliibn.). 

Riley  later  recommended  the  same  plan  for  the  bagworm  (Tkyridop- 
tenjx  c]>/i< mi  ruformt*  Haw.);  Berlese  in  Italy  recommended  it  for  the 
grapevine  Cochylis,  and  Silvestri  for  the  olive  fly  (Dacus  olese  Kossi), 
for  Prays  oleellus  Fab.,  and  for  Asphondu'Ha  lupini  Silv. 

Writing  on  the  Hessian  fly,  Marchal  has  pointed  out  that  the 
destruction  of  the  stubble  remaining  in  the  field  after  harvest  may 
have  unfortunate  consequences,  for  if  this  is  done  a  little  late  there  is 
a  risk  that  all  of  the  destructive  flies  will  have  emerged  and  aban- 
doned the  stubble,  exposing  to  destruction  only  the  parasites  whose 
part  would  have  been  to  stop  the  invasion  the  following  year.  Mar- 
chal also  points  out  that  KielTer  has  shown  that  one  of  the  measures 

1  Riley,  C.  V.  Fourth  Report  on  the  Insects  of  Missouri,  p.  40,  1871; 

3  An  excellent  article  covering;  these  general  questions  was  published  by  Decaux  in  the  Journal  of  the 
National  Horticultural  Society  of  France,  vol.  22,  pp.  158-184,  1899. 
a  Cotton  Insects,  pp.  230-231,  Washington,  1879. 


20 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


advised  for  'the  destruction  of  the  wheat  midge  (Contarinia  tritici 
Kirby),  namely,  burning  the  debris  after  thrashing,  has  only  an 
injurious  effect,  for,  while  it  is  true  that  the  pupae  of  the  midge  are  to 
be  found  in  this  debris,  it  should  be  remembered  that  the  healthy 
nonparasitized  larvae  of  the  midge  transform  in  the  ground,  while 
those  which  remain  in  the  heads  are,  on  the  contrary,  parasitized. 

Still  another  method  of  encouraging  parasites  is  pointed  out  by 
Marchal  and  Silvestri.  It  is  to  cultivate  in  the  olive  groves  various 
plants  upon  which  allied  insects  live  which  are  parasitized  by  the  same 
species  of  parasites  as  the  olive  fly.  This  idea,  independently  devel- 
oped in  the  United  States,  has  been  practically  used  by  Hunter  in  the 
fight  against  the  cotton-boll  weevil.  Allied  insects  feeding  in  certain 
weeds  along  the  borders  of  the  cotton  fields  have  parasites  capable  of 
attacking  the  boll  weevil.  Careful  study  of  the  biology  of  these  allied 
weevils  and  of  their  parasites  resulted  in  the  gaining  of  the  information 
that  if  the  weeds  are  cut  at  a  certain  time  the  parasites  are  forced  to 
attack  the  cotton-boll  weevil  in  order  to  maintain  their  existence; 
actual  experimentation  has  resulted  in  the  very  considerable  increas- 
ing of  the  percentage  of  parasitism  of  the  cotton-boll  weevil  in  this 
way. 

THE  TRANSPORTATION  OF  PARASITES  FROM  ONE  PART  OF  A  GIVEN 
COUNTRY  TO  ANOTHER  PART. 

In  1872  attempts  were  made  by  Dr.  William  Le  Baron,  at  that  time 
State  entomologist  of  Illinois,  to  transport  ApJielinus  mali  Le  Baron, 
a  parasite  of  the  oyster-shell  scale  of  the  apple  (Lepidosa  plies  ulmi  L.) 
from  one  part  of  the  State  of  Illinois  to  another  portion  of  the  same 
State  where  the  parasite  seemed  to  be  lacking.  Some  slight  success 
was  reported,  and  at  the  end  of  the  year  it  was  stated  that  the  para- 
site had  become  domiciled  in  the  new  locality,  but,  as  this  parasite 
subsequently  proved  to  be  one  of  general  American  distribution,  the 
experiment  can  not  be  said  to  have  been  worth  while  except  in  a  very 
small  way. 

In  France,  F.  Decaux,  above  quoted,  in  1872,  made  some  experi- 
ments in  the  transportation  of  parasites  from  one  locality  to  another. 

Riley,  in  his  third  report  as  State  entomologist  of  Missouri  (1870)^ 
in  considering  two  parasites  of  the  plum  curculio,  stated  that  lie 
intended  the  following  year,  if  possible,  to  rear  enough  specimens  of 
S'tr/(t!])ftus  nirculioitis  Fitch  to  send  at  Least  a  dozen  to  every  county 
seat  in  the  State  and  have  them  liberated  in  someone's  peach  orchard. 
There  seems,  however,  to  be  no  record  that  this  was  ever  done. 

In  1880,  in  his  report  on  the  parasites  of  the  Coccidas  in  the  collec- 
t  ion  of  the  Depart  nient  of  Agriculture,1  the  senior  author  called  atten- 
tion  to  the  fact  that  with  the  parasites  of  scales  the  matter  of  trans- 

'  Annual  Report  U.  B.  Department  of  Agriculture  for  1880,  p.  351. 


PREVIOUS  WORK  WITH  INSECT  PARASITES. 


k21 


Fig.  1. 


■Polygnotus  hiemalis,  a  parasite  of  the  Hessian  By: 
Greatly  enlarpe.l.   |  From  Webster.) 


Adult. 


portation  from  one  part  of  the  country  to  another  becomes  easy,  since 
all  that  has  to  be  done  is  simply  to  collect  twigs  bearing  the  scales, 
preferably  during  the 
winter  months,  and 
carry  them  to  non- 
protected regions, 
the  parasites  being 
dormant  and  pro- 
tected each  by  the 
scale  of  the  coccid 
which  it  had  de- 
stroyed; and  it  was 

specifically  recom- 
mended that  the  im- 
portant parasite  of 
the  black  scale  {Safe- 
st tin  <>h  n  Bern,  i,  de- 
scribed in  the  article 
a<  TimuH'irn  culifor- 

nic&j  could  he  readily 

carried  from  California  and  utilized  to  destroy  Lecaniuni  .scales 
in  the  Southeast. 

Ivxcellent  work  in  this  direction  ha  been  done  of 
late  years  by  the  Bureau  of  Entomology.  In  the  study 
of  the  Hessian  fly  {Mayeticla  destructor  Say),  under 

Prof.  F.  M.  Webster,  early -sown  plats  of  wheat  at 
i^.  0<  Lansing,  Mich.,  and  Marion.  Pa.,  in  1906,  were  very 
seriously  attacked  by  the  BEessian  fly,  but  when  ex- 
amined carefully  at  a  later  date  fully  90  per  cent  of  the 
flaxseeds  (pupa)  were  found  to  have  been  stung  by  a 
hyinenopterous  parasite,  Pohjgnatus  hiemalis  Forbes 
CngB,  1,  2),  and  to  contain  its  developing  larva?.  A 
field  of  wheat  near  Sharpsburg,  Md..  was  found  to  be 
infested  by  the  fly,  and  examination  indicated  the  al>- 
sence  of  the  parasite.  On  April  S,  1907,  a  Large  num- 
ber of  the  parasitized  flaxseeds  from  Marion,  Pa., 
were  brought  to  Sharpsburg  and  placed  in  the  field. 
On  July  8  an  examination  of  the  Sharpsburg  field 
showed  that  the  parasites  had  taken  hold  to  such  an 
extent  that  of  the  large  number  of  flaxseeds  taken  and 
brought  to  the  laboratory  for  investigation  not  one 
was  found  which  had  not  been  parasitized.  Additional 
material  secured  from  Sharpsburg  in  the  spring  of  1908 
in  the  same  locality  showed  all  of  the  Hessian  flies  to  be  parasitized. 

In  the  same  way  excellent  results  have  been  obtained  in  the  investi- 
gation of  the  cotton-boll  weevil,  under  Mr.  W.  D.  Hunter.    In  the 


Fig.  2—  Polygnotus 
hiemalis:  Adults 
which  have  de- 
veloped within 
the  "flaxseed" 
of  the  Hessian 
fly  and  are  ready 
to  emerge.  Much 
enlarged.  (From 
Webster.) 


22 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


summer  of  1906  a  number  of  parasites  were  taken  from  Waco,  Tex., 
and  liberated  in  a  cotton  field  near  Dallas,  Tex.,  and  apparently  by 
this  means  the  mortality  rate  due  to  parasites  was  raised  in  a  few 
weeks  about  9  per  cent.  Later,  parasites  were  introduced  from  Texas 
into  Louisiana  and  increased  the  mortality  of  the  weevil.  Work  of 
this  character  is  still  being  carried  on  by  Mr.  Hunter,  and  elaborate, 
although  as  yet  unsuccessful,  experiments  have  been  made  by  Web- 
ster in  the  transfer  of  the  hymenopterous  parasite  Lysiphlebus  tritici 
Ashm.  (fig.  3)  from  southern  points  into  Kansas  wheat  fields  for  the 
destruction  of  the  spring  grain  aphis  or  so-called  " green  bug"  (Toxop- 
tera  graminum  Rond.),  definite  results  being  prevented  by  the  occur- 
rence of  the  parasite  throughout  the  range  of  the  destructive  insect, 
parasitic,  as  it  is,  upon  other  species  of  plant  lice. 

Prof.  S.  J.  Hunter,  of  the  University  of  Kansas,  however,  in  the 
Bulletin  of  the  University  (vol.  9,  p.  2)  states  that  he  was  able,  in 
1908,  to  hasten  the  destruction  of  the  Toxoptera  in  Kansas  by  the 
importation  of  Lysiphlebus  from  some  other  point. 

In  the  last  two  years 
some  very  interesting 
work  has  been  carried 
on  by  the  State  Horticul- 
tural Commission  of  Cal- 
ifornia in  the  way  of  col- 
lecting Coccinellidse  on  a 
large  scale  in  their  hiber- 
nating quarters,  boxing 

Fig.  3.— Lysiphlebus  tritici  attacking  a  grain  aphis.   Enlarged.      them    and  Sending"  them 
(From  Webster.)  '  ,  6 

to  different  parts  01  the 
State  for  use  against  plant  lice  upon  truck  crops.  The  biennial  report 
of  the  commissioner  of  horticulture  for  1907-8,  published  in  Sacra- 
mento in  1909,  for  example,  indicates  that  50,000  specimens  of  the 
ladybird  beetles  Hippodamia  convergens  Guer.  and  Coccinella  cali- 
fornica  Mann,  had  been  so  collected.  This,  however,  was  very  small 
compared  to  the  scale  upon  which  these  insects  were  collected  dur- 
ing the  winter  of  1909-10.  Mr.  E.  K.  Carnes,  of  the  commission, 
writing  to  the  Bureau  of  Entomology  under  date  of  March  14,  1910, 
makes  the  following  statement: 

We  have  quite  a  sight  at  the  insectary  now — over  a  ton  of  Hippodamia  convergens, 
boxed  in  (50,000  lots  each,  screened  cases,  and  in  our  own  cold  storage.  We  handle 
them  in  large  rages,  run  them  into  a  chute,  and  handle  like  grain.  They  are  for  the 
melon  growers  of  the  Imperial  Valley. 

This  species  collects  in  large  numbers  late  in  summer  and  early  in 
the  autumn  al  the  bases  of  plants  in  the  mountain  valleys  and  can 
easily  be  collected  by  the  sackful.  The  actual  good  accomplished  by 
the  distribution  of  these  ladybirds  among  the  melon  growers  has  not 


PKKVIOL'S  WORK   WITH  INSECT  PARASITES. 


23 


yet  been  reported  upon,  bul  theoretically  speaking  the  experiment 
should  have  excellent  results. 

Till;  TRANSFER  OF  BENEFICIAL  INSECTS  FROM  ONE  COUNTRY  TO 

ANOTHER. 

Early  Attempts. 

Dr.  Asa  Fitch,  for  many  years  State  entomologist  of  New  York, 
was  proba  lily  the  first  entomologist  in  America,  or  elsewhere  for  that 
matter,  to  take  into  serious  consideration  the  question  of  the  transfer 
of  beneficial  insects  from  one  country  to  another.  In  1854,  following 
a  disastrous  attack  upon  the  wheat  crop  of  the  eastern  United  States 
by  the  wheat  midge  ((  ontari n'm  tritici  Kirby),  a  species  that  had  been 
accidentally  introduced  from  Europe  during  the  early  part  of  that 
century,  Dr.  Fitch,  who  had  made  a  careful  study  of  the  insect  both 
in  this  country  and  from  the  European  records,  was  struck  with  the 
fact  that  in  Europe  the  inseel  in  ordinary  seasons  did  no  damage,  and 
that  when  occasionally  it  became  so  multiplied  as  to  attract  notice  it 
was  but  a  transitory  evil  which  subsided  soon  and  was  not  heard  of 
again  for  a  number  of  years.  He  was  a  ware  that  in  Europe  certain 
parasites  of  this  insect  were  found,  and.  comparing  the  insects  taken 
from  wheat  in  flower  in  Fiance  with  those  taken  from  wheat  in  flower 
in  New  York,  he  found  that  in  France  the  wheat  midge  constituted 
but  7  pei-  cent  of  t  he  insects  t  bus  taken,  while  its  pa  rasit  es  constituted 
So  per  cent:  whereas  in  New  York  the  wheat  midge  formed  59  per 
cent  of  the  insects  thus  captured,  and  there  were  no  certain  parasites. 
He  speculated  as  to  the  cause  for  this  extraordinary  difference  and 
wrote: 

Then'  must  he  a  cause  for  this  remarkable  difference.  What  can  that  cause  he? 
I  ran  impute  it  to  only  one  tiling;  we  here  are  destitute  of  nature's  appointed  means 
for  repressing  and  subduing  tin's  insect.  Those  other  inserts  which  have  been  created 
for  the  purpose  of  quelling  this  species  and  keeping  it  restrained  within  its  appropriate 
sphere  have  never  yet  readied  our  shores.  We  have  received  the  evil  without  the 
remedy.  And  thus  the  midge  is  able  to  multiply  and  flourish,  to  revel  and  riot,  year 
after  year,  without  let  or  hindrance.  This  certainly  would  seem  to  be  the  principal  if 
not  the  sole  cause  why  the  career  of  this  insect  here  is  so  very  different  from  what  it  is 
in  the  Old  World. 

Quite  naturally  after  this  train  of  reasoning  had  entered  his  brain, 
Dr.  Fitch  made  an  effort  to  introduce  the  European  parasites  of  the 
wheat  midge,  and  in  May,  1855,  addressed  a  letter  to  John  Curtis, 
the  famous  English  economic  entomologist,  and  at  that  time  president 
of  the  Entomological  Society  of  London,  informing  him  of  the  immense 
amount  of  damage  done  by  the  midge  in  America  and  suggesting  the 
manner  in  which  parasitized  larvae  could  be  secured  in  England  and 
transmitted  alive  to  this  country.  Mr.  Curtis  was  ill  and  on  the  point 
of  starting  for  the  Continent,  but  laid  the  letter  before  the  Entomolog- 
ical Society  of  London,  which  resulted  in  the  adoption  of  a  resolution 


24 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


to  the  effect  that  if  any  member  of  the  society  should  be  able  to  find 
parasitized  midges  he  should  send  them  to  Dr.  Fitch. 

Nothing  ever  came  of  this  effort,  but  it  is  of  interest  on  account  of 
its  apparent  priority  over  other  experimentation  of  this  kind. 

The  next  international  attempt  seems  to  have  been  made  in  1873, 
when  Planchon  and  Riley  introduced  into  France  an  American 
predatory  mite  (Tyroglyphus  phylloxerx  Riley)  which  feeds  on  the 
grapevine  Phylloxera  in  the  United  States.  The  mite  became  estab- 
lished, but  accomplished  no  appreciable  results  in  the  way  of  checking 
the  famous  grapevine  pest. 

In  1874  efforts  were  made  to  send  certain  parasites  of  plant  lice 
from  England  to  New  Zealand,  but  without  results  of  value,  although 
Coccinella  undecimpunctata  L.  is  said  to  have  become  established. 

In  1883  Riley  imported  the  braconid  Apanteles  glomeratus  into  the 
United  States  from  Europe,  where  it  is  an  abundant  enemy  of  the 
imported  cabbage  worm  (Pontia  rapse  L.).  This  species  has  since 
established  itself  in  the  United  States  and  has  proved  a  valuable 
addition  to  the  North  American  fauna. 

The  Australian  Ladybird  (Novius  Cardinalis  Muls  (in  the  United  States). 

But  all  previous  experiments  of  this  nature  were  completely  over- 
shadowed by  the  remarkable  success  of  the  importation  of  ( Vedalia) 
Novius  cardinalis  Muls.  (fig.  4),  a  coccinellid  beetle,  or  ladybird, 
from  Australia  into  California  in  1889.  The  orange  and  lemon  groves 
of  California  had  for  some  years  been  threatened  with  extinction  by 
the  injurious  work  of  the  fluted  or  cottony  cushion  scale  {leery a  pur- 
chasi  Mask.)  a  large  scale  insect  which  the  careful  investigations  of 
Prof.  Riley  and  his  force  of  entomologists  at  the  United  States 
Department  of  Agriculture  had  shown  to  have  been  originally 
imported,  by  accident,  from  Australia  or  from  New  Zealand,  where  it 
had  originally  been  described  by  the  New  Zealand  coccidologist,  the 
late  W.  M.  Maskell.  The  Division  of  Entomology  had  been  for  several 
years  engaged  in  an  active  campaign  against  this  insect,  and  had  dis- 
covered washes  which  could  be  applied  at  a  comparatively  slight  ex- 
pense and  which  would  destroy  the  scale  insect.  It  had  also  in  the 
course  of  it  s  investigations  discovered  the  applicability  of  hydrocyanic- 
acid  gas  under  tents  as  a  method  of  fumigating  orchards  and  destroy- 
ing the  scale.  The  growers,  however,  had  become  so  thoroughly  dis- 
heartened by  the  ravages  of  the  insect  that  they  were  no  longer  in  a 
frame  of  mind  to  use  even  the  cheap  insecticide  washes,  and  many  of 
them  were  desl  toying  their  groves.  In  the  meantime,  through  some 
correspondence  in  the  search  for  the  original  home  of  the  scale  insect, 
Prof.  Kilev  had  discovered  that  while  the  species  occurred  in  parts  of 
Australia  i(  was  not  injurious  in  those  regions.    In  New  Zealand  it 


PREVIOUS  WORK  WITH  INSECT  PARASITES. 


25 


also  occurred,  but  was  abundant  and  injurious.  He  therefore  argued 
that  the  insect  was  probably  introduced  from  Australia  into  New  Zea- 
land, and  that  its  abundance  in  the  latter  country  and  its  relative 
scarcity  in  Australia  were  due  to  the  fact  that  in  its  native  home  it 
was  held  in  subjection  by  some  parasite  or  natural  enemy,  and  that  in 
the  introduction  into  New  Zealand  the  scale  insect  had  been  brought 
in  alone.  The  same,  thing,  he  argued,  had  occurred  in  the  case  of  the 
introduction  into  the  United  States.  He  therefore,  in  his  annual 
report  for  1886,  recommended  that  an  effort  be  made  to  study  the 
natural  enemies  of  the  scale  in  Australia  and  to  introduce  them  into 
California  ;  and  the  same  year  the  leading  fruit  growers  of  California 
in  convention  assembled  petitioned  Congress  to  make  appropriations 
for  the  Department  of  Agriculture  to  undertake  this  work.  In  Feb- 
ruary, 1SS7,  the  Department 
of  Agriculture  received  speci- 
mens of  an  Australian  para- 
site of  Ice rv a  from  the  late 
Frazier  S.  Crawford,  of  Ade- 
laide, South  Australia.  It 
was  a  dipterous  insect  known 
as  Lestophonus  ieeryx  Will., 
and  for  some  t  hue  it  was  con- 
sidered} both  by  Prof.  Riley 
and  his  correspondents  and 
agents,  that  the  importation 
of  this  particular  parasite 
offered  the  best  chances  for 
good  results. 

Neither  the  recommenda- 
tions of  Prof.  Iviley  nor  of 
the  then  commissioner  of 
agriculture.  Hon.  Norman  J. 
Colman,  nor  the  petitions  of  the  California  horticulturists  gained 
the  needed  congressional  appropriations,  and,  since  there  appeared 
at  that  time  annually  in  the  bills  appropriating  to  the  entomo- 
logical service  of  the  Department  of  Agriculture  a  clause  prevent- 
ing travel  in  foreign  parts,  it  became  necessary  to  gain  the  funds 
for  the  expense  of  the  trip  to  Australia  from  some  other  source. 
A  movement  was  started  in  California  to  raise  these  funds  by 
private  subscription,  but  it  was  never  carried  through.  In  an 
address  given  by  Prof.  Riley  before  the  California  State  Board  of 
Horticulture  at  Riverside,  CaL,  in  1S87,  he  repeated  his  recommenda- 
tions. During  the  summer  of  1887  he  was  absent  in  Europe,  and  the 
senior  author,  who  was  at  that  time  the  first  assistant  entomologist 
of  the  department,  by  correspondence  secured  from  Mr.  Crawford 
numerous  specimens  of  Icerya  infested  by  the  Lestophonus  above 


I  k;.  4.— The  Au>traliin  ladybird  (  Xoiius  cardinalis),  an 
ini|)(»rit'<l  enemy  of  (he  fluted  scale:  a,  Ladybird  larv;e 
feeding  on  adult  female  and  egg  sac;  6,  pupa;  r ,  adult 
ladybird;  d,  oringe  twig,  showing  scales  and  lady- 
birds, a-c,  Enlarged;  <J,  natural  size.  (From  Mar- 
latt.) 


26 


PARASITES  OF  GTPSY  AND  BROWN-TAIL  MOTHS. 


mentioned.  During  the  winter  of  1887-88  preparations  were  being 
made  for  an  exhibit  of  the  United  States  at  the  Melbourne  Exposi- 
tion, to  be  held  during  1888,  and  Prof.  Riley,  after  interviewing  the 
Secretary  of  State,  who  had  charge  of  the  funds  appropriated  for  the 
exposition,  was  enabled  to  send  an  assistant,  Mr.  Albert  Koebele,  to 
Australia  at  the  expense  of  this  fund.  This  result  was  hastened,  and 
Mr.  Koebele's  subsequent  labors  were  aided  by  the  fact  that  the 
commissioner  general  of  the  United  States  to  the  exposition  was  a 
California  man,  Mr.  Frank  McCoppin,  and  his  recommendation,  joined 
to  that  of  Prof.  Riley,  decided  the  Secretary  of  State  in  favor  of  the 
movement.  In  order  to  partially  compensate  the  exposition  authori- 
ties for  this  expenditure,  another  assistant  in  the  Division  of  Ento- 
mology, Prof.  F.  M.  Webster,  was  sent  out  to  make  a  special  report  to 
the  commission  on  the  agricultural  features  of  the  exposition.  Mr. 
Koebele,  who  sailed  from  San  Francisco  August  25,  1888,  was  thor- 
oughly familiar  with  all  the  phases  of  the  investigation  of  the  cottony 
cushion  scale,  and  had  for  some  time  been  stationed  in  California 
working  for  the  Department  of  Agriculture.  His  salary  was  con- 
tinued by  the  department  and  his  expenses  only  were  paid  by  the 
Melbourne  Exposition  fund.  He  made  several  sendings  of  the  Les- 
tophonus  parasite  to  the  station  of  the  Division  of  Entomology  of  the 
Department  of  Agriculture  at  Los  Angeles,  where,  under  the  charge 
of  Mr.  D.  W.  Coquillett,  a  tent  had  been  erected  over  a  tree  abun- 
dantly infested  with  the  scale  insect;  but  it  was  soon  found  that  the 
Lestophonus  was  not  an  effective  parasite. 

On  October  15  Mr.  Koebele  found  the  famous  ladybird  (Vedalia) 
Novius  cardinalis  in  North  Adelaide,  and  at  once  came  to  the  con- 
clusion that  this  insect  would  prove  effective  if  introduced  into  the 
United  States.  His  first  shipments  were  small,  but  others  continued 
from  that  date  until  January,  1889,  when  he  sailed  for  New  Zealand 
and  made  further  investigations.  Carrying  with  him  large  supplies 
of  Vedalia  cardinalis,  the  effective  ladybird  enemy,  he  arrived  in  San 
Francisco  on  March  18,  and  on  March  20  they  were  liberated  under 
the  tent  at  Los  Angeles,  where  previous  specimens  which  had  survived 
the  voyage  by  mail  had  also  been  placed. 

The  ladybird  larvge  attacked  the  first  scale  insect  they  met  upon 
being  liberated  from  the  packing  cages.  Twenty-eight  specimens  had 
been  received  on  November  30  by  Mr.  Coquillett,  44  on  December  29, 
57  on  January  24,  and  on  April  12  the  sending  out  of  colonies  was 
begun,  so  rapid  had  been  the  breeding  of  the  specimens  received  alive 
from  Australia.  By  June  12  nearly  11,000  specimens  had  been  sent 
out  to  208  different  orchardists,  and  in  nearly  every  case  the  colonizing 
of  the  insect  proved  successful.  In  the  original  orchard  practically 
all  of  the  scale  insects  were  killed  before  August,  1889,  and,  in  his 
annual  report  for  that  year,  submitted  December  31,  Prof.  Riley 


PREVIOUS  WORK  WITH  INSECT  PARAS  H  I  S. 


27 


reported  that  the  cottony  cushion  scale  was  practically  no  Longer  a 
factor  to  he  considered  in  the  cultivation  of  oranges  and  lemons  in 
California.  The  following  season  this  statement  was  fully  justified, 
and  since  that  time  the  cottony  cushion  scale,  or  white  scale,  or  fluted 
scale,  as  it  is  called,  has  no  longer  been  a  factor  in  California  horti- 
culture. Rarely  it  begins  to  increase  in  numbers  at  some  given  point, 
but  the  Australian  ladybirds  are  always  kept  breeding  at  the  head- 
quarters of  the  State  Board  of  Horticulture  at  Sacramento,  and  such 
outbreaks  are  speedily  reduced.  In  fact,  it  lias  been  difficult  for  the 
State  horticultural  authorities  to  keep  a  sufficient  supply  of  scale 
insect  food  alive  for  the  continued  breeding  of  the  ladybirds. 

The  same  insect  was  introduced  direct  from  California  into  New 
Zealand  at  a  later  date,  and  the  same  good  results  were  brought  about. 
The  Icerya  is  no  longer  a  feature  in  horticulture  in  New  Zealand. 

No  vies  i\  Portugal. 

Still  a  third  striking  instance  of  the  value  of  the  Australian  ladybird 
was  seen  later  in  the  case  of  Portugal.  T&rya  purcha8%  was  probably 
introduced  into  that  country  in  the  late  eighties  or  early  nineties  from 
her  colonies  in  the  A/ores,  to  w  hich  point  it  was  probably  introduced 
many  years  previously  from  Australia.  The  insect  spread  rapidly 
and  threatened  the  complete  destruction  of  the  orange  and  lemon 
groves  along  the  banks  of  the  River  Tagus.  In  September,  1896, 
persons  in  Portugal  applied  to  the  senior  author  for  advice  as  to  the 
most  efficacious  means  of  lighting  the  scale  insect,  and  a  reply  was 
made  urging  them  to  make  an  effort  to  introduce  I  Vedalia)  Novius 
card'inalls  and  sending  information  aa  bo  the  BUCCOSS  of  the  inseel  in 
California.  In  October,  1  S<»7,  the  chief  of  the  bureau  was  able  to 
secure,  through  the  kindness  of  the  State  Board  of  Agriculture  of 
California,  about  60  specimens  of  the  ladybird,  which  were  sent  by 
direct  mail  from  Washington  packed  in  moss.  But  live  reached  Por- 
tugal alive,  but  these  were  so  successfully  cared  for  that  there  was  a 
numerous  progeny.  Another  sending  was  made  on  the  22(1  of  Novem- 
ber lollowing.  These  were  received  on  the  ll'th  of  December  and 
proved  successful.  Karly  in  September,  1N{)8,  the  statement  was 
published  in  Lisbon  newspapers  that  already  colonies  or  stocks  of  the 
Vedalia  had  been  established  on  4S7  estates,  whence  naturally  many 
others  were  formed  by  radiation;  gardens  and  orchards  that  were 
completely  infested  and  nearly  ruined  were  already  entirely  clean  or 
well  on  the  way  toward  becoming  so.  Since  that  time  the  pest  has 
almost  entirely  disappeared.  The  bureau  would  not  have  been  able 
to  assist  the  Portuguese  Government  to  this  admirable  result  had  it 
not  been  for  the  enlightened  policy  of  the  State  Board  of  Horticulture 
of  California  in  continuing  the  breeding  in  confinement  of  these  preda- 


28 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


ceous  beetles  long  after  the  apparent  great  necessity  for  such  work 
had  disappeared  in  California,  and  had  it  not  been  for  the  courtesy  of 
the  board  in  promptly  placing  material  at  its  disposal. 

Icerya  in  Florida. 

The  general  effect  of  the  California  success  on  the  horticultural 
world  at  large  was  striking,  but  not  wholly  beneficial.  Many  enthu- 
siasts concluded  that  it  was  no  longer  worth  while  to  use  insecticidal 
mixtures,  and  that  all  that  was  necessary  in  order  to  eradicate  any 
insect  pest  to  horticulture  or  to  agriculture  was  to  send  to  Australia 
for  its  natural  enemy.  The  fact  that  the  Vedalia  preys  only  upon 
Icerya  and  perhaps  some  very  closely  allied  forms  was  disregarded, 
and  it  was  supposed  by  many  fruit  growers  that  it  would  destroy  any 
scale  insect.  Therefore  the  people  in  Florida  whose  orange  groves 
were  suffering  from  the  long  scale  (LepidosapJies  gloveri  Pack.)  and 
the  purple  scale  (LepidosapJies  heckii  Xewm.)  sent  to  California  for 
specimens  of  the  Vedalia  to  rid  their  trees  of  these  other  scale  pests. 
Their  correspondents  in  California  sent  them  specimens  of  the  beetle 
in  a  box  with  a  supply  of  Iceryas  for  food.  When  they  arrived  in 
Florida  the  entire  contents  of  the  box  were  placed  in  an  orange  grove. 
The  result  was  that  the  beneficial  insects  died,  and  the  Icerya  gained 
a  foothold  in  Florida,  a  State  in  which  it  had  never  before  been  seen. 
It  bred  rapidly  and  spread  to  a  considerable  extent  for  some  years, 
and  did  an  appreciable  amount  of  damage  before  it  was  finally 
subdued. 

Novrus  in  Cape  Colony. 

Prior  to  the  introduction  of  Xovius  into  Portugal,  Icerya  puschasi 
1  laving  been  established  at  the  Cape  of  Good  Hope,  the  beneficial 
ladybird  was,  after  an  unsuccessful  attempt,  carried  from  California 
to  Cape  Town  by  Mr.  Thomas  Low,  member  of  the  Legislative 
Assembly  of  Cape  Colony,  and  on  the  29th  of  January,  1892,  living 
specimens  were  placed  in  perfect  condition  in  the  hands  of  the  depart- 
in  en t  of  agriculture  of  Cape  Colony.  These  specimens  multiplied 
and  were  reenforced  late  in  1892  by  a  new  sending  from  Australia 
made  by  Koebele.  At  the  present  time  the  Novius  is  perfectly 
naturalized  at  the  Cape. 

Novius  in  Egypt  and  the  Hawaiian  Islands. 

At  the  same  time,  through  the  United  States  Department  of  Agri- 
culture and  the  courtesy  of  the  State  Board  of  Horticulture  of  Cali- 
fornia, the  Novius  was  sent  to  Egypt  to  prey  upon  an  allied  scale 
insert,  Icerya  ;r(/!/]>fiaca  Dough,  which  was  doing  great  damage  to 
citrus  trees  and  to  fig  trees  in  the  gardens  of  Alexandria,  Egypt. 
Six  adull   insects  and  several  larvae  arrived  in  living  condition  at 


PREVIOUS  WORK  WITH  INSECT  PARASITES. 


29 


Alexandria.  These  multiplied  so  rapidly  as  to  eause  an  almost 
complete  disappearance  of  the  scales.  Later  the  latter  began  to 
increase,  but  the  Novius  had  not  died  out  and  also  increased.  The 
Icerya  is  still  held  in  check  in  a  very  perfect  way. 

In  1S90  the  Novius  had  been  introduced  into  the  Hawaiian  Islands 
for  work  against  Icerya  purchasi  with  the  same  success. 

Icerya  in  Italy. 

In  1000  Icerya  purchasi  was  found  also  in  Italy,  in  a  small  garden 
at  Porticij  upon  orange  trees.  By  the  autumn  of  1900  it  had  mul- 
tiplied so  abundantly  that  the  owner  of  the  garden  tried  to  stop 
the  trouble  by  cutting  down  the  trees  most  badly  infested,  without 
bothering  himself  with  the  others,  so  that  the  infestation  continued. 
When  Prof.  Berlese's  attention  was  called  to  it  an  attempt  was  first 
made  to  destroy  it  by  insecticides  without  success,  and  then  Nanus 
card't nails  was  imp* tiled  from  Portugal  and  from  America.  The 
following  June  the  Ladybird  in  both  sexes  was  distributed  in  the 
garden,  prospered  wonderfully,  and  multiplied  rapidly.  In  July  the 
results  were  already  evident;  one  could  hardly  find  patches  of  Icerya 
which  did  not  show  the  work  of  Xovius,  and  at  the  end  of  the  month 
it  was  difficult  to  find  adult  Iceryas  with  which  to  continue  the 
rearing  in  the  laboratory  for  food  for  the  reserve  supply  of  Novius. 
At  the  present  time  the  multiplication  of  the  scale  insect  has  been 
reduced  to  the  point  of  practically  no  damage,  but  the  original  infes- 
tation still  persists  and^the  area  of  distribution  of  the  scale  insect 
is  slow  l  v  enlarging.  It  i^  found  n<»!  only  al  Portici  but  in  -ill  tin1 
little  towns  around  Vesuvius  and  in  the  gardens  in  Xaples;  but  the 
presence  of  the  ladybird  allows  the  culture  of  oranges  and  lemons 
to  go  on  without  interruption. 

Icerya  in  Syria. 

The  latest  utilization  of  the  beneficial  Xovius  is  recorded  by  Sil- 
vestri. It  seems  that  about  the  year  1905  Icerya  made  its  appearance 
in  Syria,  and  in  July,  1007,  Selim  Ali  Slam  wrote  to  Prof.  Silvestri 
that  it  had  spread  so  greatly  about  Beirut  that  it  had  almost 
destroyed  the  trees.  Silvestri  sent  a  shipment  of  Novius  in  July, 
1007,  and  another  one  in  August.  The  result  was  the  same  in  Syria 
as  it  had  been  in  other  countries;  the  Novius  multiplied  greatly  and 
produced  the  desired  elfect.1 

The  Reasons  for  the  Success  of  Novius. 

It  thus  appears  that  in  the  Novius  we  have  an  almost  perfect 
remedy  against  Icerya.    There  have  been  no  failures  in  its  intro- 

1  Since  the  above  was  written  (in  the  autumn  of  1909)  still  another  success  with  Xovius  has  been  by  its 
carriage  from  California  to  Formosa  by  I>r.  T.  Shiraki,  the  entomologist  of  the  Formosan  Government, 
wlio  writes,  under  date  of  Jan.  28,  1910:  "To-day  it  has  relieved  the  region  from  Icerya  and  has  reduced 
their  number  to  a  practically  negligible  quantity." 


30 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


duction  to  any  one  of  the  different  countries  to  which  it  has  been 
carried.  Its  success  has  been  more  perfect  than  that  of  any  other 
beneficial  insect  that  has  so  far  been  tried  in  this  international  work. 
There  are  good  reasons  for  this — reasons  that  do  not  hold  in  the 
relations  of  many  other  beneficial  insects  to  their  hosts.  In  the  first 
place,  the  Icerya  is  fixed  to  the  plant;  it  does  not  fly,  and  crawls  very 
slowly  when  first  hatched,  and  later  not  at  all.  The  Novius,  however, 
is  active,  crawls  rapidly  about  in  the  larval  state,  and  flies  readily 
in  the  adult.  In  the  second  place,  the  Novius  is  a  rapid  breeder,  and 
has  at  least  two  generations  during  the  time  in  which  a  single  genera- 
tion of  the  host  is  being  developed.  In  the  third  place,  the  Novius 
feeds  upon  the  eggs  of  the  Icerya.  And  in  the  fourth  place,  it  seems 
to  have  no  enemies  of  its  own.  This  is  a  very  strange  fact,  since  other 
ladybirds  are  destroyed  by  several  species  of  parasites.  For  example, 
as  will  be  shown  later,  native  American  ladybird  parasites  brought 
about  a  great  mortality  in  the  larvae  of  the  Chinese  ladybird  imported 
from  China  into  America  at  a  later  date  by  Marlatt.  The  hymenop- 
terous  parasites  of  the  widespread  genus  Homalotylus  feed  exclu- 
sively in  ladybird  larvae,  which  are  frequently  also  fairly  packed  with 
the  minute  hymenopterous  parasites  of  the  genus  Syntomosphyrum, 
while  the  adults  are  often  destroyed  by  Perilitus,  Microctonus,  and 
Euphorus. 

The  astonishing  results  of  the  practical  handling  of  Novius  drew 
attention  more  forcibly  than  ever  before  to  the  possibilities  of  this 
kind  of  warfare  against  injurious  insects,  and  although  its  perfect 
success  as  an  individual  species  has  never  been  duplicated,  very 
many  efforts  in  this  direction  have  been  made,  some  of  which  have 
met  with  measurable  success  and  some  with  very  positive  results  of 
value. 

Introduction  op  Entedon  epigonus  Walk,  into  the  Unted  States. 

In  1891,  with  the  assistance  of  Mr.  Fred  Enock,  of  London,  Riley 
introduced  puparia  of  the  Hessian  fly  (Alayetiola  destructor  Say) 
infested  with  the  chalcidid  parasite  Entedon  epigonus  Walk,  into 
America.  These  were  distributed  among  several  entomologists  dur- 
ing the  spring  of  1891.  One  American  generation  was  carefully 
followed  by  Forbes  in  Illinois,  and  four  years' later  (in  May,  1895) 
the  species  was  recovered  by  Ashmead  at  Cecilton,  Md.,  where  a 
colony  had  been  placed  in  1891.  Thus  the  introduction  was  appar- 
ently successful,  but  if  the  species  still  exists  in  the  United  States 
it  must  be  rare,  since  extensive  rearings  of  Hessian-fly  parasites  have 
been  made  by  agents  of  the  Bureau  of  Entomology  in  many  different 
pails  of  the  country  during  the  past  few  years  and  not  a  single  speci- 
men of  the  Entedon  lias  been  recognized.  The  Maryland  locality, 
however,  it  should  be  stated,  has  not  been  visited  by  an  entomologist 
since  Ashmead 's  trip  in  May,  1895. 


PREVIOUS  WORK   WITH  INSECT  PARASITES. 


31 


Other  Introductions  by  Koebele  into  California. 


The  overwhelming 


Mr.  Koebele  took  a  second  trip  to  Australia,  New  Zealand,  and  the 
Fiji  Islands  while  still  an  agent  of  the  Department  of  Agriculture, 
but  at  the  expense  of  the  California  State  Board  of  Horticulture,  and 
in  1S93  he  resigned  from  the  United  States  Department  of  Agriculture 
and  was  employed  by  the  State  Board  of  Horticulture  of  California 
for  still  another  trip  to  Australia  and  other  Pacific  islands.  He  sent 
home  a  large  number  of  beneficial  insects,  nearly  all  of  them,  however, 
coccinellids.  Several  of  these  species  were  established  in  California, 
and  are  still  living  in  different  parts  of  the  State, 
success  of  the  importation  of  Xorius  cardinalis 
was  not  repeated,  but  one  of  the  insects 
brought  over  at  that  time,  namely,  the  ladybird 
beetle  RJiizohius  ventralis  Er.  (fig.  5),  an  enemy 
of  the  so-called  black  scale  [Saissttia  o/< «  Bern.) . 
WAS  colonized  in  various  parts  of  California,  and 
in  districts  where  the  climatic  conditions  proved 
favorable  its  work  was  very  satisfactory,  nota- 
bly in  the.  olive  plantations  of  Mr.  Ellwood 
Cooper,  near  Santa  Barbara.  Hundreds  of 
thousands  of  the  beetles  were  distributed  in 
California  and  in  some  localities  kept  the  black 
scale  in  check.  Away  from  the  moist  coast  re- 
gions, however,  they  proved  to  be  less  efTect ive. 


J 


INTXRNATIONJJL  Work 


w  ith  Kn  kmies  of  tin:  Bl  if  k 
Scale. 


Fig.  5. — Rhizobius  untralis, 
an  imported  enemy  of  the 
black  scale:  a.  Adult  lady- 
bird; 6,  larva.  Much  en- 
kirp'd.   (From  Marlatt.) 


It  will  here  be  convenient  to  drop  the  chrono- 
logical sequence  with  which  the  subject  in  hand 
has  been  treated  and  to  refer  to  the  introduction 
of  a  very  successful  parasite  of  the  black  scale, 
whose  work  against  this  destructive  enemy  to 
olive  and  citrus  culture  in  California  for  a  time 
seemed  second  only  to  the  success  of  the  Xovius 
against  the  Icerya.  In  1859  Motchulsky  described,  under  the  name 
ScuteUista  cyanea  (fig.  6),  a  very  curious  little  hymenopterous  parasite 
reared  by  Nietner  from  the  coffee  scale  in  Ceylon.  Subsequently 
this  parasite  became  accidentally  introduced  into  Italy  and  was  sent 
to  the  senior  author  for  identification  by  Dr.  Antonio  Berlese  as  a 
parasite  of  the  wax  scale,  Ceroplastes  rusci  L.  As  there  are  wax 
scales  (Ceroplastes  florid ensis  Comst.  and  C.  cirri  pcdijnr  mis  Comst.) 
which  are  more  or  less  injurious  in  Florida  and  the  Gulf  States,  an 
attempt  was  made,  with  Berlese's  assistance,  to  introduce  this  para- 
site at  a  convenient  location  at  Baton  Rouge,  La.,  with  tbe  further 


32 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


assistance  of  Prof.  H.  A.  Morgan  at  that  place.  Berlese's  sending 
arrived  in  good  condition,  and  the  parasites  issued  at  Baton  Rouge 
and  immediately  bega \i  to  attack  the  native  species.  The  importa- 
tion was  successful  for  a  time,  but  the  introduced  species  was  finally 
reduced  to  an  insignificant  number,  presumably  through  the  attacks 
of  hyperparasites. 

In  the  meantime  Prof.  CP.  Lounsbury,  an  American  occupying 
the  position  of  entomologist  of  the  department  of  agriculture  at  the 
Cape  of  Good  Hope,  on  his  arrival  at  the  Cape  in  1395  and  searching 
for  the  usual  cosmopolitan  scale  insects  on  fruit  trees,  failed  to 

find  the  black  scale.  He  com- 
mented on  this  fact  in  one  of 
his  first-published  papers,  and 
alluded  to  the  severity  of  the 
scale  as  a  pest  in  California. 
Shortly  afterwards  he  found 
the  species,  and  sent  the  senior 
avthor  specimens  for  identifi- 
cation in  1895,  together  with 
parasites  which  he  had  reared 
from  it.  Subsequent  cor- 
respondence showed  other 
species,  and  eventually  Scutel- 
lista  cyanea  was  forwarded. 
Writing  to  Mr.  Lounsbury 
September  14,  1896,  the  chief 
of  the  bureau  made  the  follow- 
ing suggestion:  "I  think  para- 
sitized black  scales  could  be 
sent  to  California  to  advan- 
tage. Mr.  Alexander  Craw 
would  be  the  proper  person  to 
to  whom  to  send  them." 
Mr.  Lounsbury  made  further 
studies,  and  commented  in  his  1898  report  on  the  existence  of 
parasites.  When  this  report  met  the  eye  of  Mr.  E.  M.  Ehrhorn,  of 
the  Stale  horticultural  commission,  Mr.  Ehrhorn  wrote  Mr.  Louns- 
bury, under  date  of  December  22,  1899,  asking  him  to  send  a  colony 
of  the  parasite.  Mr.  Lounsbury  had  in  the  meantime,  in  a  letter 
to  the  senior  author,  suggested  that  in  order  to  gain  authority  to 
spend  time  over  the  matter  and  incur  necessary  expense  it  would  be 
desirable  for  the  Secretary  of  Agriculture  of  the  United  States  to 
make  a  formal  requesl  for  these  parasites  to  the  secretary  of  agri- 
culture of  (  ape  (  olouy.    This  was  done,  and  in  May,  1900,  Lounsbury 


Fig.  G.—ScutcUista  cyanea,  an  imported  parasite  of  the 
black  scale:  Dorsal  and  lateral  views  of  adult,  with 
enlarged  details.  Greatly  enlarged.  (From  Howard.) 


PREVIOUS  WORK  WITH  INSECT  PARASITES. 


33 


secured  leave  of  absence  and  started  for  America,  carrying  with  him 
a  box  of  parasitized  scales,  and  landed  at  New  York  on  June  2. 
His  box  of  parasites  was  at  once  forwarded  to  Washington,  and  the 
Bureau  of  Entomology  notified  Mr.  Ehrhorn  by  telegram,  repacked 
the  box,  and  sent  it  to  California.  Mr.  Ehrhorn  succeeded  in  tem- 
porarily establishing  the  Scutellista  indoors  and  out  around  his  home 
at  Mountain  View,  Cal.  September  19,  1900,  Mr.  C.  YV.  Mally, 
Lounsbury's  assistant,  sent  two  more  boxes  by  post  direct  to  Cali- 
fornia, addressing  them  to  S.  F.  Leib,  of  San  Jose,  notifying  the 
senior  author  to  wire  Mr.  Ehrhorn  to  be  on  the  lookout  for  them.  A 
third  lot  was  sent  October  31  of  the  same  year.  These  later  sendings 
were  small,  and  both  failed  to  yield  living  parasites.  More  were 
requested,  and  on  Lounsbury's  return  to  South  Africa  a  box  was 
shipped  in  cool  chamber  to  England  and  thence  direct  to  California 
by  express,  Lounsbury's  letter  of  February  28,  1901,  to  the  bureau 
stating:  "To  avoid  extra  delay  in  transmission  the  box  goes  direct 
to  California,  but  will  you  kindly  have  a  message  sent  to  (  raw  to 
advise  him  of  its  coining  ?"  rnfortunately  the  box  was  detained  by 
a  customs  odicer  at  New  York,  but  the  bureau  secured  its  release  by 
the  Government  dispatch  agent,  Mr.  I.  P.  Koosa.  A  tew  parasites 
emerged  after  arrival,  but  failed  t<>  propagate.  October  1,  1901, 
Lounsbury  started  another  sending  by  letter  post  to  insure  quick 
transit  and  noninterference  by  customs.  These  boxes  were  delivered 
to  Mr.  Craw  on  October  31.  Only  four  females  of  the  Scutellista 
were  reared  by  Mr.  Craw,  and  probably  to  these  four  females  are  due 
all  of  the  Scutellistas  subsequently  occurring  in  California.  This  is 
the  full  story  of  the  introduction  of  the  species,  taken  from  the  letter 
files  of  t he  Bureau  of  Entomology  and  the  letter  files  of  Mr.  Louns- 
bury iu  ( 'ape  Tow  ii. 

Mr.  Craw  was  remarkably  successful  in  his  rearings,  and  during  the 
following  three  years  constantly  distributed  colonies  in  different  por- 
tions of  California.  By  July,  1902,  he  had  distributed  25  colonies. 
It  was  in  the  southern  part  of  the  State  that  the  parasite  did  its  best 
work,  and  there  for  a  time  it  surpassed  the  most  sanguine  expecta- 
tions of  everyone.  It  was  established  in  every  county  south  of  Point 
Conception  and  had  become  very  plentiful  in  Los  Angeles,  Orange, 
and  San  Diego  Counties.  In  the  colonization  districts  by  midsum- 
mer, 1903,  it  was  estimated  that  over  90  per  cent  of  the  black  scale 
had  been  destroyed.  A  year  or  so  later  there  was  great  mortality 
among  these  parasites  caused  by  a  sudden  increase  in  numbers  of 
a  predatory  mite,  Pediculoides  ventricosus  New]),  (fig.  7),  which 
destroyed  the  larvae  in  vast  numbers.  The  Scutellista  gradually 
recovered  from  this  attack,  and  is  at  present  to  be  found  in  very 
many  localities  in  California,  keeping  the  black  scale  partly  in  check. 
95G770— Bull.  91—11  3 


34 


PAEASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Another  enemy  of  the  black  scale  was  imported  in  1901.  It  is  a 
small  moth,  Erastria  scitula  Ramb.  (fig.  8),  the  larva  of  which  feeds 
in  the  bodies  of  mature  scales,  each  larva  destroying  a  number  of 
scales.  An  effort  had  been  made  by  Riley  to  import  this  insect  from 
Fi  ance  in  1892,  but  without  success.  In  1901  Berlese  sent  the  senior 
author  living  pupae,  which  were  at  once  forwarded  to  Craw  and- 
Ehrhorn  in  California.  It  was  reported  in  1902  that  the  insects  had 
been  reared  and  liberated  in  Santa  Clara,  Los  An- 
geles, and  Niles,  CaL,  but  if  the  species  was  estab- 
lished in  the  State  it  has  not  flourished  and  has 
not  recently  been  found. 

A  similar  lepidopterous  insect,  Thalpochares  coc- 
ciphaga  Meyrick,  was  brought  over  from  Australia 
in  the  summer  of  1892  by  Koebele  and  left  by 
him  at  Hay  wards,  CaL,  but  the  species  evidently 
died  out. 

The  Hawaiian  Work. 


Fig.  7.  ~Pediculoid.es 
ventricosus.  Greatly 
enlarged.  (From 
Marlatt.) 


In  1893  Koebele  resigned  from  the  service  of 
the  State  of  California  and  entered  the  employ- 
ment of  the  then  newly  established  Hawaiian  Re- 
public for  the  purpose  of  traveling  in  different 
countries  and  collecting  beneficial  insects  to  be  introduced  into 
Hawaii  for  the  purpose  of  destroying  injurious  insects.  Before 
leaving  California  he  had  introduced  a  very  capable  ladybird,  Crypto- 
Ixrnus  montrouzieri  Muls.,  which  feeds  upon  mealy  bugs  of  the  genus 


1  [O.  ^.—Erastria  scitula,  an  imported  enemy  of  the  black  scale:  a,  Larva  from  below;  6,  same,  from 
above;  c,  same,  in  case;  d,  case  of  full-grown  larva;  e,  pupa;  /,  moth.  Enlarged.  (After  Rou- 
zaud.) 

Pseudococcus.  This  insect  flourished,  especially  in  southern  Cali- 
fornia, and  on  arrival  in  Hawaii  he  found  that  coffee  plants  and 
certain  other  trees  were  on  the  point  of  being  totally  destroyed  by 
the  allied  scale  insect  known  as  Pulvinaria  psidii  Mask.    He  at 


PBEVIOUS  WORK  WITH  INSECT  PARASITES. 


35 


once  introduced  this  same  Cryptolsemus,  which  is  an  Australian 
insect,  with  the  result  that  the  Pulvinaria  was  speedily  reduced  to  a 
condition  of  harmlessness. 

It  may  be  incidentally  stated  that  within  the  past  year  efforts  have 
been  made  by  the  Bureau  of  Entomology  to  send  the  Cryptohemus  to 
Malaga,  Spain,  for  the  purpose  of  feeding  upon  a  Dactylopius.  The 
first  attempt  was  unsuccessful,  and  the  results  of  the  last  attempt 
have  not  yet  been  learned. 

Another  importation  of  Koebele's  into  Hawaii  was  the  ladybird 
CoccineUa  repanda  Thunh.  from  Ceylon.  Australia,  and  China,  which 
was  successful  in  destroying  plant  lice  upon  sugar  cane  and  other 
crops.  Writing  in  1896,  Mr.  R.  C.  L.  Perkins  stated  that  Koebele 
had  already  introduced  eight  other  Species  which  had  become  natu- 
ralized and  were  reported  as  doing  good  work  against  certain  scale 
insects.  Among  other  things  he  introduced  Chalcis  obscurata  Walk, 
from  China  and  Japan,  which  multiplied  enormously  at  the  expense 
of  an  injurious  lepidopterous  larva  (Omiodes  bhukhurui  Butl.)  which 
had  severely  attacked  banana  and  palm  trees. 

Koebele's  travels  from  1X94  to  1N<>6  were  through  Australia.  China. 
Ceylon,  and  Japan.  In  L899  he  left  for  Australia  and  the  Fiji  Islands, 
and  sent  many  ladybirds  and  parasites  to  1  lawaii,  especially  to  attack 
the  scale  Ceroplastes  rubens  Mask.  The  Hawaiian  Sugar  Planters' 
Association,  an  organization  which  was  responsible  for  Koebele's 
appointment,  subsequently  employed  Mr.  K.C.  L.  Perkins.  Mr.  G.  W. 
Kirkaldy.  Mr.  F.  \Y.  Terry,  Mr.  O.  II.  Swezey,  and  Mr.  F.  Muir.  By 
the  close  of  l'.KVJ  sugar  planters  were  especially  anxious  concerning 
the  damage  of  an  injurious  leafhopper on  the  Bugar  cane,  PerhinsieUa 
saccliaricida  Kirk.  This  insect  had  been  accidentally  introduced 
from  Australia  about  L897,  had  increased  rapidly,  and  by  1902  had 
become  a  serious  pest.  Koebele  had  made  an  effort  to  introduce 
parasites  of  leafhoppers  from  the  Tinted  States  into  Hawaii,  with 
unsatisfactory  results,  and  consequently  in  the  spring  of  1004  Koe- 
bele and  Perkins  visited  Australia  and  collected  all  possible  parasites 
of  different  leafhoppers.  Altogether  they  succeeded  in  finding  more 
than  100  species.  Of  these  the  following  hymenopteruus  parasites 
are  said  to  have  become  acclimated  in  Hawaii:  Anngrns  (t  wo  species) , 
Paranagrus  optabilis  Perk,  and  P.  perforator  Perk,  and  OoUtnistichus 
beatus  Perk.  These  species  are  all  parasit  ic  upon  the  eggs  of  the  leaf- 
hopper.  By  the  end  of  1906  observations  upon  a  certain  plantation 
indicated  the  destruction  of  86.3  per  cent  of  the  eggs  by  these  para- 
sites. In  addition  to  these  egg  parasites  certain  proctotrypid 
parasites  of  hatched  leafhoppers  have  apparently  become  established, 
namely,  Ilaplogonatopus  vitiensis  Perk.,  Pseudogonatopus  (two 
species),  and  Ecihrodelphax  faircMldii  Perk.  Three  predatory 
beetles,  namely,  Verania  frenata  Erichs.,  V.  lineola  Fab.,  and  Calli- 
neda  testudinaria  Muls..  were  also  distributed  in  large  numbers. 


36  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

The  practical  results  of  these  importations  seem  to  have  been 
excellent.  There  seems  to  be  no  doubt  that  the  parasites  have  been 
the  controlling  factor  in  the  reduction  of  the  leafhoppers. 

The  good  work  in  Hawaii  is  still  continuing.  Koebele  is  now  on  a 
visit  to  Europe  to  import  the  possible  parasites  of  the  horn  fly 
(Hxmatobia  serrata  Rob.-Desv.),  Muir  is  trying  to  find  an  enemy  to 
a  sugar-cane  borer  (RTiabdocnemis  obscurus  Boisd.),  and  other  similar 
work  is  under  way. 

An  Importation  op  Clerus  prom  Germany. 

An  early  attempt  to  import  beneficial  species  into  the  United 
States  was  made  in  1892  by  Dr.  A.  D.  Hopkins,  then  entomologist 
to  the  West  Virginia  Agricultural  Experiment  Station  and  now  of 
the  Bureau  of  Entomology.  A  destructive  barkbeetle,  Dendroc- 
tonus  frontalis  Zimm.,  was  extremely  injurious  in  that  State  in  the 
years  1889  to  1892,  and  Hopkins  made  the  effort  to  import  from 
Europe  another  beetle,  {Clerus)  Thanasimus  formicarius  L.,  from 
Germany.  In  Germany  he  collected  more  than  a  thousand  specimens 
of  the  Clerus,  which  he  took  with  him  to  West  Virginia  and  distrib- 
uted in  various  localities  infested  by  the  barkbeetle.  The  following 
year,  however,  the  barkbeetle  disappeared  almost  completely  from 
other  causes,  and  the  Clerus  has  not  since  been  found. 

Marlatt's  Journey  for  Enemies  op  the  San  Jose  Scale. 

Another  and  later  expedition  was  that  undertaken  by  Mr.  C.  L. 
Marlatt,  of  the  Bureau  of  Entomology,  in  search  of  the  natural 
enemies  of  the  San  Jose  scale.  The  question  of  the  original  home 
of  the  San  Jose  scale  (Aspidiotus  perniciosus  Comst.)  had  been  a 
mooted  point.  As  is  well  known,  it  started  in  this  country  in  the 
vicinity  of  San  Jose,  CaL,  in  the  orchard  of  Mr.  James  Lick,  who  had 
imported  trees  and  shrubs  from  many  foreign  countries.  Mr.  Lick 
died  before  the  investigation  started,  and  no  records  of  his  impor- 
tations were  to  be  found.  The  scale  was  not  of  European  origin, 
since  it  does  not  occur  on  the  continent.  In  the  course  of  investiga- 
tion it  was  found  that  it  occurred  in  the  Hawaiian  Islands,  in  Japan, 
and  in  Australia,  but  in  the  case  of  Australia  and  the  Hawaiian 
Islands  it  was  shown  that  it  had  been  carried  on  nursery  stock  from 
California.  In  1897  plants  entering  the  port  of  San  Francisco  from 
Japan  were  discovered  by  Mr.  Craw  to  carry  the  San  Jose  scale. 
Correspondence,  however,  seemed  to  point  to  the  conclusion  that  it 
had  also  been  introduced  into  Japan  from  the  United  States.  In 
1901-2  Mr.  Marlatt  made  a  trip  of  exploration  in  Japan,  China,  and 
other  eastern  countries,  lasting  more  than  a  year.  Six  months 
were  spent  in  Japan,  and  after  a  thorough  exploration  the  con- 
clusion was  reached  that  the  scale  is  not  a  native  of  that  country 


PREVIOUS  WORK  WITH  INSECT  PARASITES. 


37 


and  that  wherever  it  occurs  there  it  has  spread  from  a  center  of 
imported  American  fruit  trees.  Finally,  as  a  result  of  this  extended 
trip,  the  native  home  of  the  San  Jose  scale  was  found  to  be  in  northern 
China  in  a  region  between  the  Tientsin-Peking  Road  and  the  Great 
Wall,  and  its  original  host  plant  was  found  to  be  a  little  haw  apple 
which  grows  wild  over  the  hills.  Into  that  region  no  foreign  intro- 
ductions of  fruit  or  fruit  trees  had  ever  been  made,  and  the  fruits 
in  the  markets  were  all  of  the  native  sorts.  Here  in  China  was  found 
everywhere  present  a  little  ladybird,  Chilocorus  sintilix  Rossi  (fig.  9), 
feeding  in  all  stages  upon  the  San  Jose  scale.    One  hundred  and  fifty 


Fig.  9.— The  Asiatic  ladybird  (Chilororus  similis)  ,an  Imported  enemy  of  the  San  Jose  scale:  a,  Beoond 
larval  stage;  6,  cast  skin  of  same;  <  ,  full-grown  larva;  d,  method  of  pupation,  the  pupa  being  retained 
in  the  split  larval  skin;  e,  newly  emerged  adult,  not  yet  colored;  /.fully  colored  and  perfect  adult. 
All i  ilarged  to  the  same  scale.   (From  Marlatt.) 

or  two  hundred  specimens  of  the  beetle  were  shipped  by  Mr.  Marlatt 
to  Washington  alive,  but  all  but  two  perished  during  the  winter.  One 
at  least  of  the  two  survivors  was  an  impregnated  female,  and  began 
laying  eggs  early  in  April.  From  this  individual  at  least  200  eggs 
were  obtained,  the  work  being  done  in  breeding  jars.  After  some  hun- 
dred larva?  had  been  hatched  from  these  eggs  the  beetles  were  placed 
on  a  large  plum  tree  in  the  experimental  orchard  and  protected  by  a 
wire-screen  cage  covering  the  tree.  The  stock  increased  very  rapidly, 
and  during  August  shipments  to  various  eastern  experiment  stations 
were  begun,  about  1,000  specimens  being  sent  out.    At  the  end  of  the 


38 


PAEASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


first  summer 'there  remained  of  the  stock  at  Washington  about  1,000 
beetles.  Among  the  colonies  sent  out  the  best  success  was  obtained 
in  Georgia.  An  orchard  at  Marshall  ville  in  that  State,  containing 
some  17,000  peach  trees  and  covering  about  85  acres,  adjoined  a 
larger  orchard  containing  about  150,000  trees,  all  scatteringly  in- 
fested with  the  scale.  The  ladybirds  were  liberated  in  August,  1902, 
in  the  smaller  orchard,  and  an  examination  made  11  months 
later  indicated  that  they  were  rapidly  spreading  and  would  soon 
cover  the  orchard.  The  number  of  beetles  in  all  stages  present  was 
estimated  at  nearly  40,000.  Colonies  established  in  the  Northern 
States  perished.  In  the  South  the  almost  universal  adoption  of  the 
cheap  and  satisfactory  lime-sulphur  washes  destroyed  the  possi- 
bility of  rapid  multiplication  and  destroyed  the  majority  of  the  bene- 
ficial insects.  This  species  has  not  been  found  recently,  but  prob- 
ably exists  in  Georgia.  The  introduction  and  establishment  of  the 
species  was  successful,  but  it  was  practically  killed  out  by  the  cheap 
and  satisfactory  washes  in  general  use.  Without  the  washes  the 
probabilities  are  that  the  ladybird  would  be  found  at  the  present 
time  occurring  in  great  numbers  in  southern  orchards. 

The  Parasites  of  Diaspis  Pentagona  Targ. 

For  a  number  of  years  the  mulberry  plantations  of  Italy  had 
suffered  severely  from  the  attack  of  the  insect  known  as  the  West 
Indian  peach  scale  (Diaspis  peniagona  Targ.).  Tins  insect  occurs 
in  the  United  States  and  is  widely  distributed  in  other  parts  of  the 
world.  In  the  United  States,  however,  it  is  not  especially  injurious. 
In  1905/ at  the  request  of  Berlese,  the  writer  sent  parasitized  Diaspis 
from  Wasliington  to  Florence,  Italy.  One  of  the-  parasites  which 
issued,  Prospaltella  herlesei  How.,  was  artificially  reared  in  Florence 
by  Berlese  and  his  assistants,  and  at  the  time  of  present  writing  has 
been  so  thoroughly  established  in  several  localities  that  the  ultimate 
reduction  of  the  Diaspis  to  harmless  numbers  is  confidently  antic- 
ipated by  Berlese.  Similarly,  Silvestri  at  Portici  has  introduced 
the  same  species  from  America,  and  also  certain  ladybirds,  and  is 
making  the  effort  to  import  the  parasites  of  tins  species  from  its 
entire  range. 

The  Work  of  Mr.  George  Compere. 

Mr.  George  Compere,  employed  jointly  by  Western  Australia  and 
California  as  a  searcher  for  beneficial  insects,  for  several  years  has  been 
traveling  in  different  parts  of  the  world  in  search  of  beneficial  insects 
which  he  has  either  sent  or  brought  to  California  and  Western  Aus- 
tralia. One  of  the  most  interesting  of  his  achievements  was  sending 
living  specimens  of  ( 'a//'n  p/iialtrs  mcssor  Grav.,  an  ichneumon  fly,  from 
Spain  to  California.    This  species  is  a  parasite  of  the  codling  moth. 


PREVIOUS  WORK  WITH  INSECT  PARASITES. 


39 


In  California  this  ichneumon  fly  has  been  reared  with  great  success 
and  has  been  sent  out  in  large  numbers  from  the  headquarters  of  the 
State  board  of  horticulture.  In  the  field,  however,  it  is  apparently  not 
succeeding,  and  there  is  no  evidence  that  the  numbers  of  the  codling 
moth  have  been  at  all  reduced  by  it.  Nor  is  it,  according  to  Froggatt, 
effective  in  Spain. 

Mr.  Compere  has  collected  many  beneficial  species  attacking  many 
different  injurious  insects.  '  He  is  an  indefatigable  worker,  and  Ins 
untiling  qualities  and  his  refusal  to  accept  failure  are  well  shown  in 
his  search  for  the  natural  enemies  of  the  fruit  fly  of  Western  Australia, 
OeratiHs  capitate  Wied.  lie  vi>ited  the  Philippine  Islands,  China, 
Japan,  California,  Spain,  returning  to  Australia,  afterwards  visiting 
Ceylon  and  India,  and  subsequently  Brazil.  In  Brazil  he  succeeded 
in  finding  an  ichneumon  fly  and  a  staphvlinid  beetle  feeding  upon 
fruit-fly  larva1.  He  collected  some  numbers  and  carried  them  to 
Australia  in  living  condition,  prematurely  reporting  success.  The 
fruit  fly  is  a  pest  in  South  Africa,  and  follow  ing  the  announcement  of 
Compere's  importations  Claude  Fuller  and  C.  P.  Lounsbury  pro- 
ceeded from  Africa  to  Brazil  to  get  the  same  parasites.  The  result  of 
this  journey  was  discouraging.  They  did  not  find  the  predatory 
staphvlinid,  but  obtained  a  braconid  parasite,  Op'nllus  trimacitlatus 
Spin.;  they  also  concluded  from  information  gained  that  the  fruit  fly 
had  been  hit  rod  need  into  South  America  more  recent  lv  than  into  South 
Africa.  The  material  carried  home  died.  Compere  left  Australia 
again  about  the  close  of  I'M)};  went  to  Spain  for  more  codling-moth 
parasites,  and  then  went  on  to  Brazil,  collecting  more  fruit-fly  para- 
sites and  carrying  them  to  Australia.  The  Brazilian  natural  enemies, 
however,  did  not  succeed,  and  in  1906  he  proceeded  to  India  to  collect 
parasites  of  a  related  fly  of  the  genus  Dacus,  finding  several  and  tak- 
ing them  to  Western  Australia.  He  arrived,  however,  in  the  middle 
of  winter,  and  the  insects  perished.  In  May,  1907,  once  more  this 
indefatigable  man  returned  to  India,  and  in  a  few  months  collected 
70,000  to  100, 000  parasitized  pupa\  and  brought  them  to  Perth, 
Western  Australia,  in  good  condition  on  the  7th  of  December.  It  is 
reported  that  the  parasites  issued  from  this  material  in  great  numbers 
and  in  three  distinct  species.  In  April,  1908,  it  was  reported  that 
120,000  parasites  had  been  obtained  and  distributed,  20,000  of  them 
having  been  sent  to  South  Africa.  The  writer  has  not  seen  any 
definite  reports  of  success  in  the  control  of  the  fruit  fly  by  these  para- 
sites, but  surely  Compere  deserves  great  credit  for  his  efforts. 

Work  with  the  Egg  Parasite  of  the  Elm  Leaf-beetle. 

In  1905  Dr.  Paul  Marehal,  of  Paris,  published  in  the  Bulletin  of  the 
Entomological  Society  of  France  for  February  22  a  paper  entitled 
"  Biological  observations  on  a  parasite  of  the  elm  leaf-beetle,"  to 


40  PAKASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

which  he  gave  the  name  TetrasticJius  xanthomelxnx.  In  this  very 
interesting  article  Dr.  Marchal  called  attention  to  the  fact  that  the 
elm  leaf-beetle  had  multiplied  for  several  years  in  a  disastrous  way 
about  Paris,  skeletonizing  the  leaves  in  the  parks  and  along  the  ave- 
nues. In  1904  the  ravages  apparently  stopped,  and  MarchaFs  obser- 
vations indicated  that  this  was  largely  due  to  the  work  of  this  egg 
parasite.  He  studied  the  life  history  of  the  parasite  carefully  during 
that  year  at  Fontenay-aux-Roses  and  published  his  full  account  the 
following  February. 

Visiting  Dr.  Marchal  in  June,  1905,  after  the  publication  of  this  inter- 
esting article,  the  senior  author  asked  him  whether  he  had  been  able 
to  make  the  further  observations  promised  in  the  article,  and  he  re- 
plied that  the  elm  leaf-beetle  had  so  entirely  disappeared  in  the  vicin- 
ity of  Paris  that  he  had  not  been  able  to  do  so.  The  visitor  urged  him 
to  make  an  effort  through  his  correspondents  to  secure  parasitized 
eggs  of  the  beetle  for  sending  to  the  United  States  in  an  effort  to  intro- 
duce and  establish  this  important  parasite  on  this  side  of  the  Atlantic. 
It  was  considered  hopeless  to  attempt  the  introduction  that  summer, 
as  the  time  was  so  late  and  it  was  not  then  known  in  what  part  of 
France  the  elm  leaf-beetle  could  be  found  abundantly.  During  1906 
practically  the  same  conditions  existed.  A  locality  was  found,  but 
the  parasites  did  not  seem  to  be  present.  In  1907,  reaching  Paris 
about  the  1st  of  May,  the  visitor  again  reminded  Dr.  Marchal  of  his 
desire  to  import  the  parasite  into  the  United  States,  and  meeting  M. 
Charles  Debreuil,  of  Melun,  the  subject  was  again  brought  up  and  M. 
Debreuil  later  in  the  season  forwarded  eggs  of  the  beetle  to  the  United 
States,  winch  were  promptly  sent  to  the  parasite  laboratory  at  North 
Saugus,  Mass.,  but  the  time  was  too  late,  and  the  parasites  had 
emerged  and  died. 

In  April,  1908,  the  Entomological  Society  of  France  published  in  its 
bulletin  (No.  7,  p.  86)  a  request  from  the  senior  author  that  eggs  of  the 
elm  leaf-beetle  should  be  sent  to  the  United  States  for  the  purpose  of 
rearing  parasites.  This  notice  brought  a  speedy  and  effective  response. 
About  the  20th  of  May  Prof.  Valery  Mayet,  of  Montpellier,  France,  a 
personal  friend,  secured  a  number  of  leaves  of  the  European  elm  car- 
rying egg  masses  of  the  beetle,  placed  them  in  a  tight  tin  box,  and 
mailed  them  to  Washington.  They  were  received  May  28,  and  at 
once  forwarded  to  the  junior  author  at  the  parasite  laboratory  at 
Melrose  Highlands.  On  opening  the  box  the  junior  author  found  a 
considerable  number  of  active  adults  of  the  parasite.  Most  of  them 
were  placed  in  a  large  jar  containing  leaves  of  elm  upon  which  were 
newly  deposited  masses  of  the  elm  leaf-beetle  eggs.  Probable  ovipo- 
sit ion  was  noticed  within  an  hour  after  the  receipt  of  the  sending. 
There  were  probably  somewhat  more  than  100  adults  received  in  the 
shipment  and  very  few  emerged  from  the  imported  egg  masses  after 


PREVIOUS  WORK  WITH  INSECT  PARASITES. 


41 


the  first  day.  The  adults  lived  certainly  for  35  days.  Reproduction 
occurred  in  the  experimental  jars,  and  the  adults  secured  by  this 
laboratory  reproduction  were  liberated  in  two  localities  near  Boston 
and  parasitized  eggs  were  sent  to  Prof.  J.  B.  Smith  at  Xew  Brunswick, 
X.  J.,  Prof.  M.  V.  Slingerland  at  Ithaca.  X.  Y.,  and  others  to  Washing- 
ton. The  first  of  the  Massachusetts  colonies  consisted  of  about  600 
parasites  inclosed  in  an  open  tube  tied  to  a  tree  in  the  Harvard  yard, 
Cambridge,  Mass.,  on  June  22,  Mr.  Fiske  thinks  that  more  than  100 
found  their  freedom  on  the  same  day,  and  almost  certainly  all  of  the 
rest  within  a  week.  A  little  more  than  a  month  later  Mr.  Fiske 
found  parasitized  eggs  one-fourth  of  a  mile  away  from  this  colony. 
At  Melrose  Highlands  more  than  1,200  were  liberated  on  the  21st  of 
June  and  the  8th  of  July:  and  on  the  27th  of  July  fresh  native  eggs  in 
the  neighborhood  produced  parasites,  indicating  the  development  of 
a  generation  on  American  soil.  In  the  summer  of  1909  none  of  the 
parasites  was  found,  but  this  by  no  means  indicates  that  the  species 
has  not  become  established.  Both  the  eggs  and  the  parasites  are 
very  small,  and  the  writer  expects  t  hat  even  from  this  fust  experiment 
good  results  will  follow.  Arrangements  had  been  made  for  a  repeti- 
tion of  the  sending  in  May,  1909.  from  Montpellier,  this  southern 
locality  allowing  such  an  early  sending  as  to  insure  the  arrival  of  the 
parasitized  eggs  in  the  l/nited  State-  at  the  proper  time  of  the  year. 
Relying  upon  Prof.  Mayet's  promises  and  his  great  experience  as  an 
entomologist,  no  other  arrangements  were  made.  Most  unfortu- 
nately, however,  just  before  the  time  arrived  Prof.  Mayet  died,  and 
the  introduction  was  not  made.  It  should  be  stated  that  in  the  death 
of  this  admirable  man  France  lost  one  of  it  -  most  enlightened  and  able 
economic  zoologists.  It  is  hoped  to  repeat  the  introduction,  through 
the  kindness  of  Dr.  Marrhal  in  Prance  and  Prof.  Silvestri  in  Italy. 
Silvestri  has  promised  also  to  send  other  natural  enemies  of  the  elm 
leaf-beetle  from  Italy. 

Work  with  Parasites  of  Ticks. 

Ti  1907  the  senior  author  described  the  first  species  of  a  hymenop- 
terous  parasite  ever  recorded  as  having  been  reared  from  a  tick. 
The  name  given  to  it  was  Ixodiphagus  texanus,  and  it  had  been 
reared  from  the  nymphs  of  Hsemaphysalis  le ports- palustris  Pack, 
collected  on  a  cotton-tail  rabbit  in  Jackson  County,  Tex.,  by  Mr. 
J.  D.  Mitchell.  In  1908  he  described  another,  Ilunterellus  hookeri, 
reared  by  Mr.  W.  A.  Hooker  at  Dallas,  Tex.,  from  Bin  pice  plialus 
texanus  Banks  taken  from  a  Mexican  dog  at  Corpus  Christi,  Tex., 
by  Mr.  II.  P.  Wood.  Inasmuch  as  a  closely  allied  if  not  identical 
tick.  Rhipicephcihu  sanr/uineus  Latr.,  is  supposed  to  be  a  transmitter 
of  a  trypanosome  disease  in  South  Africa,  sendings  of  the  Hunterellus 
were  made  in  the  autumn  of  1908  to  Prof.  Lounsbury  at  Cape  of 


42 


PARASITES  OF  GIPSY  AND  BROWN -TAIL  MOTHS. 


Good  Hope  and  to  Mr.  C.  W.  Howard,  entomologist  to  the  govern- 
ment of  Lourenco  Marques,  Portuguese  East  Africa.  In  June,  1909, 
Mr.  C.  W.  Howard  reared  parasites  from  engorged  nymphs  of  Rhipi- 
cephalus  sanguineus  taken  from  dogs,  with  which  transmission 
experiments  with  trypanosomiasis  were  being  made.  Examination 
showed  them  to  be  Hunterellus  liookeri.  Mr.  C.  W.  Howard  is  of 
the  opinion  that  these  1909  reared  specimens  could  not  have  been 
the  offspring  of  those  sent  over  in  the  autumn  of  1908,  since,  as  he 
writes  under  date  of  September  3,  1909,  the  latter  arrived  while  he 
was  absent  in  the  Zambesi  country,  and,  as  he  was  gone  nearly  three 
months,  they  remained  on  his  desk  unopened.  When  he  returned 
they  were  all  dead.  He  kept  the  ticks  some  time,  however,  in  a 
sealed  jar  to  see  if  any  more  parasites  might  emerge,  but  none  did  so. 
In  his  opinion  there  is  absolutely  no  possibility  that  the  1909  speci- 
mens are  the  descendants  of  those  sent  from  Texas.  Of  course  Mr. 
C.  W.  Howard  is  probably  correct  in  his  surmise,  but  a  most  interest- 
ing question  arises  as  to  the  original  home  of  the  parasite.  Could  it 
have  been  carried  accidentally  from  Texas  to  Africa  at  an  earlier 
date  ?  As  a  matter  of  fact,  during  the  Boer  War  thousands  of  horses 
and  mules  were  shipped  from  southern  Texas  to  Cape  Town,  and 
much  of  this  stock  came  from  the  very  region  in  which  the  Texas 
Rhipicephalus  occurs.  Banks,  in  his  revision  of  the  ticks,1  records 
this  species  from  horses  as  well  as  from  dogs,  the  horse  record  coming 
from  New  Mexico.  The  suggestion  regarding  the  importation'  of 
horses  and  mules  from  Texas  to  Cape  Town  during  the  Boer  War 
was  made  to  the  writer  by  Mr.  W.  D.  Hunter,  who  also  suggests  that 
as  Rhipicephalus  sanguineus  occurs  throughout  Africa  and  Mediter- 
ranean Europe,  and  that  as  in  1853  several  shipments  of  camels 
were  brought  to  Texas  from  Tunis,  being  turned  loose  at  Indianola 
and  roaming  wild  throughout  the  territory  around  Corpus  Christi 
for  some  years,  it  is  possible  that  the  Rhipicephalus  was  brought  to 
Texas  on  these  camels,  and  the  parasite  as  well.  This  seems  unlikely, 
however,  since  the  parasite  had  never  been  found  in  Africa  or  Europe 
until  the  specimens  referred  to  were  reared  by  Mr.  C.  W.  Howard  in 
1909. 

Mr.  Froggatt's  Journey  to  Various  Parts  of  the  World  in  1907-8. 

As  a  result  of  a  conference  of  Australian  Government  entomologists, 
held  in  Sydney,  July  9,  1906,  and  of  a  conference  of  State  premiers, 
held  in  Brisbane,  June,  1907,  it  was  agreed  that  Mr.  W.  W.  Froggatt, 
entomologist  to  the  Department  of  Agriculture  of  the  State  of  New 
South  Wales,  should  be  dispatched  to  America,  Europe,  and  India, 
to  inquire  into  the  best  methods  of  dealing  with  fruit-flies  and  other 
pests,  the  expenses  of  the  journey  to  be  shared  by  Queensland,  South 


'  P.  8.  Depart  ment  of  Agriculture,  Bureau  of  Entomology,  Technical  Scries  No.  15,  p.  35,  1908. 


PREVIOUS  WORK  WITH  INSECT  PARASITES. 


43 


Australia,  New  South  Wales,  and  Victoria.  As  a  result  of  the  trip 
following  this  authorization,  Mr.  Froggatt  has  published  a  report  on 
parasitic  and  injurious  insects,  issued  in  1909,  in  which  he  considers, 
(1)  the  commercial  value  of  introduced  parasites  to  deal  with  insects 
that  are  pests;  (2)  the  range  and  spread  of  fruit-flies,  and  the  methods 
adopted  in  other  countries  to  check  them;  (3)  the  value  of  parasites 
in  exterminating  fruit-Hies:  (4)  the  habits  of  cosmopolitan  insect 
pests.  On  his  journey,  which  began  the  end  of  June,  1907,  Mr. 
Froggatt  visited  Hawaii,  the  United  States,  Mexico,  Cuba,  Jamaica, 
Barbados,  England,  France,  Spain,  Italy,  Austria,  Hungary,  Turkey, 
Cyprus  (spending  a  day  in  Smyrna  and  two  days  at  Beirut  on  the 
way),  Egypt,  India,  Ceylon,  and  thence  to  Australia,  stopping  in 
Western  Australia  before  his  return  to  Sydney.  In  the  course  of 
this  trip  Mr.  Froggatt  not  only  studied  the  question  of  parasites  and 
of  economic  entomology  in  general,  but  looked  into  a  large  number 
of  matters  of  agricultural  interest,  and  has  given  a  report  which 
can  not  fail  to  be  interesting  to  every  one  occupied  with  any  branch 
of  agriculture. 

With  regard  to  the  practical  handling  of  parasites,  and  especially 
international  work,  lie  i>  inclined  t«>  be  rigidly  critical.  Sis  motive 
obviously  was  to  look  everywhere  for  accomplished  results  and 
where  he  could  not  find  these  to  distinctly  state  the  fact.  lie  depre- 
cates all  claims  that  are  not  or  have  not  been  justified  by  practical 
results  of  value.  Thus,  while  admitting  the  good  work  of  the  intro- 
duced parasites  of  the  sugar-cane  leafhoppei  in  Hawaii,  he  states 
that  the  advocates  of  the  parasite  system  do  not  take  into  account 
the  alteration  of  methods  of  cultivation  which  occurred  about  the 
same  time,  namely,  the  burning  of  the  refuse  (probably  containing 
many  eggs  and  larva4)  instead  of  burying  it  as  formerly,  and  the 
introduction  of  new  varieties  of  cane  more  resistant  to  the  leaf- 
hoppers.  In  California,  he  admits  the  value  of  the  introduction  of 
the  Australian  ladybird,  but  states  that  his  observations  show  that 
no  good  has  followed  the  introduction  of  the  codling-moth  parasite 
from  Spain,  although  it  had  been  claimed  previously  that  this  parasite 
would  prove  a  perfect  remedy  for  the  apple  pest,  and  pointing  out 
that  when  lie  visited  Spain  he  found  that  a  very  large  percentage  of 
the  apple  crop  is  always  infested  by  the  codling  moth.  He  states 
that  the  promises  of  the  advocates  of  the  parasite  method  in  Cali- 
fornia have  not  been  fulfilled;  that  Western  Australian  claims  that 
staphylinid  beetles  destroy  the  majority  of  the  fruit-fly  maggots  in 
Brazil,  and  that  nature's  forces  in  that  country  control  the  destruc- 
tive fruit  flies  are  to  be  contrasted  with  the  statement  of  the  South 
African  entomologists  that  only  a  few  months  after  the  visit  of  the 
W"est  Australian  entomologist  to  Brazil  they  found  that  "all  along 
the  Brazilian  coast  it  was  difficult  to  obtain  a  fruit  that  had  not  been 


44 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


punctured  by  a  fly."  The  statement  that  nature  controls  the 
destructive  fruit  flies  in  India  he  opposes,  as  a  result  of  his  own 
observations  in  India.  He  does  not  contend  that  this  work  has  not 
a  great  practical  value,  but  insists  that  it  should  be  done  by  trained 
entomologists,  and  that  full  information  of  the  habits  and  life  his- 
tories of  both  the  pests  and  their  parasites  should  be  understood 
before  liberation  is  attempted.  As  already  stated,  he  especially 
deprecates  premature  claims,  and  points  out  that  in  New  South 
Wales  the  passage  of  the  very  necessary  vegetation  diseases  bill  was 
delayed  for  some  years  by  the  outcry  "Why  should  we  be  made  to 
clean  up  our  orchards  and  spend  money,  when  the  department  can 
send  out  to  other  countries  and  get  us  parasites  that  will  do  all  that 
is  needed?"    In  conclusion  he  states: 

Let  the  whole  question  be  judged  on  its  results.  Allow  that  one  or  two  experiments 
have  shown  perfect  results;  yet  because  mealy  bugs  or  scale  insects  in  a  restricted 
locality  have  once  or  twice  been  destroyed  by  parasites,  that  can  be  no  reason  why 
the  parasite  cure  alone  should  be  forced  upon  anyone.  Its  admirers  should  be 
perfectly  honest;  and  if  a  friendly  introduced  insect  from  which,  rightly  or  wrongly, 
great  things  had  been  expected  turns  out  upon  further  trial  to  be  a  failure,  they  should 
say  so;  and  they  should  never  proclaim  results  for  a  parasite  till  those  results  have 
actually  been  proved  in  its  adopted  country,  for  the  wisest  can  never  be  sure  of  the 
results  of  any  experiment.  Economic  entomology  is  a  great  commercial  science, 
and  those  at  work  for  its  far-reaching  interests  could  do  it  no  greater  harm  than  by 
misleading  or  unproved  statements. 

Other  Work  of  this  Kind. 

Reference  has  already  been  made  to  the  importations  of  Prospal- 
tella  berlesei  into  Italy  to  attack  the  destructive  mulberry  scale, 
Diaspis  pentagona,  through  cooperative  arrangements  between  the 
senior  author  and  Prof.  Berlese,  of  Florence.  Prof.  Berlese  has  been 
successful  in  establishing  the  species,  and  believes  that  it  is  best  to  rely 
upon  this  species  only,  and  not  to  attempt  to  introduce  the  predatory 
enemies  of  the  scale,  his  idea  being  that  coccinellids  will  feed  indis- 
criminately upon  parasitized  and  unparasitized  scales  and  that  thus 
the  Prospaltella  will  not  have  a  chance  to  multiply  to  its  limit.  The 
contrary  view  is  taken  by  Prof.  Silvestri,  at  Portici,  in  the  south  of 
Italy,  and  he  has  been  making  every  effort  to  introduce  from  all  parts 
of  the  world  all  of  the  enemies,  whether  parasitic  or  predatory,  of  the 
mulberry  scale.  He  has  brought  over  and  has  had  breeding  in  his 
laboratory  at  Portici,  as  well  as  in  an  experimental  olive  orchard 
southeasl  of  Naples,  a  number  of  species  of  Coccinellidse  brought  from 
differenl  parts  of  the  world.  At  his  request,  in  May,  1910,  the  senior 
author  carried  from  Washington  a  box  containing  possibly  200  living 
specimens  of  Microweisia  misella  Lec.  and  a  few  specimens  of  (Jhilo- 
COVU8  h  'mulnerus  Muls.  These  were  carefully  packed  with  plenty  of 
food  in  a  small  paper  covered  wooden  box,  approximating  a  10-inch 
cube.    He  sailed  from  New  York  direct  to  Naples  and,  through  the 


PREVIOUS  WORK    WITH    INSECT  PARASITES. 


45 


kindness  of  the  officers  of  the  Royal  Italian  Line  steamship  Duca  di 
Genova,  was  enabled  to  suspend  the  box  by  a  cord  from  a  crossbeam  in 
the  ordinary  cold  room  of  the  steamer.  After  an  eleven  days'  passage, 
the  box  was  opened  in  Prof.  Silvestri's  laboratory  in  Portici,  and  prac- 
tically  even'  coceinellid  was  found  to' be  alive  and  in  apparently  good 
condit  ion. 

Efforts  have  been  made  by  the  Bureau  of  Entomology,  in  coopera- 
tion with  the  Pasteur  Institute  in  Paris,  to  introduce  a  large  bembecid 
wasp  (  Moimlula  caro/'uta  Fab.)  from  New  Orleans  into  Algeria  to  prey 
upon  the  tabanid  flies  concerned  in  the  carriage  of  a  trypanosome 
disease  of  dromedaries.  The  wasps  were  sent  in  their  cocoons  in  re- 
frigerating baskets  from  New  Orleans  by  direct  steamer  to  Havre  and 
from  New  York  by  direct  >t  earner  to  Havre.  There  they  were  met  by 
agents  of  the  Pasteur  Institute1,  carried  to  Marseilles  by  rail  and  thence 
by. boat  to  Algeria,  and  were  planted  under  conditions  as  closely  as 
possible  resembling  those  under  which  they  were  found  in  Louisiana, 
care  being  t  aken  to  simulate  not  only  I  lit1  character  of  the  soil  but  the 
exposure  to  light,  the  prevailing  wind  directions,  and  the  moisture 
conditions.  Adults  issued,  but  the  species  has  not  since  been  re- 
covered, although  it  is  quite  possibly  established. 

In  the  same  way  an  attempt  was  made  to  introduce  the  common 
bumblebee  linmbus  /><  nnsi/lranicus  ])c  Geer  of  the  United  States  into 
the  Philippine  Islands  for  the  purpose  of  fertilizing  red  clover.  These 
were  sent  in  refrigerating  baskets,  carried  by  hand  by  Filipino  stu- 
dents ret  u ruing  from  the  Tinted  St  ates  to  the  Philippines,  and  for  the 
most  part  in  the  pupal  stage.  These  were  properly  planted  upon 
arrival  and  reared,  and  a  few  specimens  have  been  recovered. 

In  the  summer  of  1910  Dr.  L.  P.  De  Bussy,  biologist  of  the  Tobacco 
Planters'  Association  of  Deli,  Sumatra,  visited  the  United  States  for 
the  purpose  of  investigating  damage1  to  the  tobacco  crop  by  insects 
and  disease  and  to  make  an  effort  to  import  into  Sumatra  the  parasites 
of  the  destructive  tobacco  worm  known  as  Heliothis  obsoleta  Fab. 
Already  shipments  of  an  egg  parasite,  Trxchogratmmva  prctiosa  Riley, 
have  been  made  to  Sumatra  via  Amsterdam,  but  information  as  to 
the  results  of  these  preliminary  shipments  has  not  yet  reached  this 
count  i  y. 

Prof.  C.  H.  T.  Townsend,  an  assistant  in  the  Bureau  of  Entomology, 
receiving  a  temporary  appointment  as  entomologist  to  the  Depart- 
ment of  Agriculture  of  Pern,  especially  to  study  the  injurious  work 
done  by  the  scale  insect  Hemichionaspis  minor  Mask,  on  cotton,  has 
during  the  past  year,  with  the  assistance  of  the  bureau,  imported  a 
number  of  shipments  of  Prospaltella  berlesci  from  Washington  into 
Peru.    It  is  too  early  to  announce  results. 

In  July,  1910,  Mr.  R.  S.  Woglum,  an  agent  of  the  Bureau  of  Ento- 
mology, was  sent  abroad  to  find  the  original  home  of  the  white  fly  of 


46 


PARASITES  OF  GIPSY  AXD  BROW  X-T  AIL  MOTHS. 


the  orange,  Aleyrodes  citri  K.  &  H.,  and  to  attempt  to  find  parasites 
or  satisfactory  predatory  enemies.  In  November,  1910,  he  found  the 
white  fly  at  Saharampur,  India,  and  discovered  that  it  was  killed  by  a 
fungous  disease  (lately  determined  as  a  species  already  occurring  in  the 
United  States — JLgerita  webberi — by  Prof.  H.  S.  Fawcett,  of  the  Florida 
Agricultural  Experiment  Station).  He  also  found  that  it  was  at- 
tacked by  two  species  of  CoccinellidaB  (Verania  cardoni  Weise  and 
Cryptognatha  jiavescens  Motsch.).  A  preliminary  shipment  of  the 
ladybirds  by  mail  was  apparently  unsuccessful.  Later  shipments  by 
direct  steamer  from  Calcutta  to  Boston  were  also  unsuccessful. 

At  Lahore,  India,  Mr.  Woglum  found  his  first  evidence  of  parasit- 
ism by  hymenopterous  parasites.  A  certain  proportion  of  Aleyrodes 
citri  was  found  to  contain  the  exit  holes  of  a  tine  parasite.  The 
specimens  on  leaves  sent  in  by  Mr.  Woglum  were  examined  with 
great  care.  None  of  the  full-grown  larvse  or  nymphs  contained  para- 
sites, but  five  specimens  of  a  very  minute  aphelinine  of  the  genus 
Prospaltella  were  found  dead  and  attached  to  the  orange  leaves  in 
close  viciirity  to  the  perforated  aleyrodids.  The  size  of  the  specimens 
was  such  as  to  justify  the  conclusion  that  they  had  issued  from  the 
aleyrodids,  and  their  juxtaposition  and  the  known  habits  of  the  genus 
confirm  this  conclusion.  The  species  was  described  by  the  senior 
author  as  Prospaltella  lahorensis  in  the  Journal  of  Economic  Ento- 
mology for  February,  1911,  pages  130-132.  Efforts  will  be  made  to 
import  this  parasite  into  Florida. 

The  occurrence  of  a  European  weevil,  PTiytonomus  murinus  Fab., 
in  the  alfalfa  fields  of  Utah  in  alarming  numbers  and  the  difficulty  of 
fighting  the  pest  by  mechanical  or  cultural  means  has  started  an  in- 
vestigation as  to  its  parasites  in  its  original  home.  Mr.  W.  F.  Fiske, 
of  the  Bureau  of  Entomology,  sent  from  Naples,  Italy,  on  March  17, 
1911,  a  large  lot  of  stems  of  alfalfa  containing  eggs  of  an  allied  weevil 
parasitized  by  a  minute  mymarid,  which  at  the  time  of  this  writing 
are  on  their  way  to  Utah. 

In  the  meantime  the  State  board  of  horticulture  of  California  has 
been  continuing  its  efforts  to  import  beneficial  insects  of  different 
kinds.  Mr.  George  Compere  returned  from  a  lengthy  trip  during  the 
summer  of  1910,  bringing  with  him  a  number  of  interesting  species, 
among  them  a  new  coccinellid  enemy  of  mealy  bugs  in  which  he  has 
great  faith,  and  which  promises  to  be  a  valuable  addition  to  the  insect 
fauna  of  the  United  States. 

Entomologists  and  horticulturists  all  over  the  world  have  become 
greatly  interested  in  this  aspect  of  economic  entomology  and  for  the 
immediate  future  a  great  deal  of  experimental  work  has  been  planned 
by  the  officials  of  different  countries. 


EARLY  IDEAS  ON  INTRODUCTION. 


47 


EARLY  IDEAS  ON  INTRODUCING  THE  NATURAL  ENEMIES  OF  THE 

GIPSY  MOTH. 

Promptly  with  the  discover}'  that  the  gipsy  moth  had  become 
acclimatized  in  Massachusetts,  in  1SS9  there  was  published  by  Prof. 
C.  II.  Fernald  a  special  bulletin  of  fche  Massachusetts  Agricultural 
College  Hatch  Experiment  Station,  in  which  lie  gave  popular  descrip- 
tions of  the  different  stages  of  the  insect  and  recommended  spraying 
with  Paris  green.  He  stated  that  the  insect  is  generally  held  in 
check  by  its  natural  enemies  in  Europe,  but  occasionally  becomes 
very  destructive,  and  stated  that  11  species  of  hymenopterous  para- 
sites and  several  of  dipterous  parasites  had  been  noticed  in  Europe. 
This  bulletin  was  published  in  November,  1889.  In  January.  1890, 
an  illustrated  article  on  the  gipsy  moth,  by  Riley  and  Howard,  was 
published  in  Insect  Life,1  and  a  list  of  24  European  hymenopterous 
parasites  compiled  by  Howard  was  published. 

Immediately  following  this  publication,  there  was  received  at  the 
Department  of  Agriculture,  from  Rev.  II.  Loomis,  of  Yokohama, 
Japan,  a  letter  in  which  he  stated  that  he  had  seen  reports  of  the 
ravages  of  the  gipsy  moth  in  Massachusetts  and  had  taken  consid- 
erable interest  in  the  matter.  He  also  stated  that  he  had  seen  the 
gipsy  moth  caterpillar  on  ;i  wist  aria  vine  near  his  house  in  Yokohama, 
and  that  it  had  been  attacked  and  killed  by  a  parasite.  Several  of 
the  parasites  were  sent  in  an  accompanying  box.  and  proved  to  be 

Apanteles.  Subsequent  attempts  were  made  by  Mr.  Loomis  to  send 
this  parasite  in  living  condition  both  to  the  Department  of  Agricul- 
ture and  to  the  State  of  Massachusetts,  but  all  arrived  dead,  for  the 
most  part  having  been  killed  by  secondary  parasites. 

In  March.  1S91,  a  conference  w  as  held  in  the  rooms  of  the  com- 
mittee on  agriculture  at  Boston,  at  which  were  present  Prof.  N.  S. 
Shaler,  Gen.  F.  EL  Appleton,  and  Mr.  William  K.  Sessions,  of  the 
State  board  of  agriculture;  Prof.  C.  V.  Riley,  entomologist  of  the 
Tinted  States  Department  of  Agriculture;  Prof.  C,  H.  Fernald,  ento- 
mologist of  the  State  Experiment  Station:  Mr.  S.  II.  Scudder,  a  well- 
known  entomologist ;  the  mayors  of  Medford,  Melrose,  Arlington,  and 
Maiden,  and  others.  In  the  course  of  the  conference,  which  was  held 
for  the  purpose  of  discussing  the  best  measures  to  be  taken  against 
the  gipsy  moth  by  the  State,  Prof.  Riley  advocated  an  attempt  at 
extermination  by  spraying.  Mr.  Scudder  advocated  the  destruction 
of  the  eggs,  and  in  the  course  of  the  discussion  Prof.  Riley  made  the 
following  remark: 

I  would  make  one  other  suggestion,  and  that  is.  that  as  an  auxiliary  method  it  would 
be  well  to  spend  $500  or  $600  in  sending  one  or  two  persons  abroad  next  summer  with 
no  other  object  than  to  go  to  some  section  of  northern  Europe  to  collect  and  transmit 
to  authorized  persons  here  a  certain  number  of  the  primary  parasites  of  this  species, 


•  Insect  Life,  Division  of  Entomology,  U.  S.  Department  of  Agriculture,  vol.  2.  pp.  206-211,  1890. 


48 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


which  are  known' to  check  its  ravages  over  there.  The  insect  was  undoubtedly  brought 
over  by  Trouvelot  without  any  of  its  natural  checks.  In  my  judgment  it  would  be 
well  worth  trying  to  import  its  parasites  from  abroad.  The  advantage  would  be  this: 
If  you  failed  to  exterminate  it  by  spraying,  its  parasites,  seeking  for  this  particular 
host,  would  be  more  apt  to  find  the  overlooked  or  escaped  specimens  than  man  would. 

No  action  was  taken  upon  this  suggestion,  and  the  State  author- 
ities, believing  that  such  an  attempt  would  be  useless  owing  to  the 
fact  that  their  effort  for  some  years  was  consistently  devoted  to  the 
aim  of  absolute  extermination  of  the  gipsy  moth,  perhaps  wisely 
saved  the  expense  of  a  mission  abroad  for  this  purpose.  Then,  also, 
there  was  some  hope  that  the  native  parasites,  particularly  the  ich- 
neumon flies  and  the  native  species  of  Apanteles,  as  well  as  tachina 
flies  and  some  of  the  carabid  beetles,  might  gradually  accommodate 
themselves  to  the  imported  pest  and  prove  prominent  factors  in  the 
fight  against  it. 

This  last  faint  hope,  however,  was  not  justified.  In  the  course  of 
the  careful  work  done  by  the  State  during  the  next  seven  or  eight 
years,  the  better  part  of  which  is  summarized  in  the  admirable  Report 
on  the  Gipsy  Moth,  by  Forbush  and  Fernald,  published  in  1896,  sev- 
eral native  parasites  and  predatory  insects  were  observed  to  attack 
the  gipsy  moth  in  its  different  stages,  but  at  no  time  was  the  per- 
centage of  parasitism  sufficiently  great  to  have  any  value  as  a  factor 
in  the  suppression  of  the  pest.  At  no  time  was  there  a  greater  per- 
centage of  parasitism  by  native  parasites  than  10,  whereas  the  con- 
dition in  Europe  is  such  that  the  percentage  reaches  frequently  well 
above  80.  It  may  be  worth  mentioning  that  parasitism  by  native 
species  has  never  exceeded  5  per  cent  in  any  collections  made  since  the 
present  laboratory  was  established.  It  is  nearer  2  per  cent  on  the 
average. 

In  discussions  among  the  Washington  entomologists  it  was  repeat- 
edly pointed  out  by  E.  A.  Schwarz  and  by  B.  E.  Fernow  (at  that  time 
Chief  of  the  Division  of  Forestry  of  the  United  States  Department  of 
Agriculture)  that  one  of  the  most  important  of  European  enemies  of 
the  gipsy  moth,  and  the  nun  moth  as  well,  is  one  of  the  tree-climbing 
ground  beetles  known  as  Calosoma  sycophanta  L.  There  exist  a  num- 
ber of  species  of  this  same  genus  Calosoma  in  the  United  States,  but 
none  of  them  has  the  tree-climbing  habit  developed  to  the  same  ex- 
tent as  have  Calosoma  sycophanta  of  Europe  and  its  relative  Calosoma 
inquisitor  L.  Prof.  Fernald,  writing  to  the  famous  German  authority 
on  forest  insects,  Dr.  Bernard  Altum,  early  in  1895,  asked  his  opinion 
as  i  o  1  he  advisability  of  importing  these  tree-inhabiting  ground  beetles, 
but  received  the  reply  that  such  an  importation  would  not  give  good 
results.  Prof.  Altum  considered  the  services  of  the  hymenopterous- 
parasites  of  the  old  genus  Microgaster  as  of  much  more  importance. 

In  l  he  report  just  cited  Fernald  disposed  of  the  question  of  import- 
ing parasites  in  the  following  words: 


CIRCUMSTANCES  OCCASIONING  WORK. 


49 


No  attempt  has  boon  made  to  import  parasites  thus  far  for  the  reason  that  the  law 
require!  the  work  to  be  conducted  with  direct  reference  to  the  extermination  of  the 
gipsy  moth,  and,  therefore,  the  general  destruction  of  the  insect  would  also  destroy 
the  parasites.  There  is  no  reason  why  our  native  hymenopterous  parasites  may  not 
prove  to  be  quite  as  effective  as  those  of  any  other  country,  since  there  is  no  parasite 
known  which  confines  itself  exclusively  to  the  gipsy  moth,  and.  as  has  been  Bhown, 
we  have  several  species  which  attack  it  as  readily  as  any  in  its  native  country. 

This  position  with  regard  to  the  nonimportation  so  iong  as  exter- 
mination of  the  gipsy  moth  was  the  end,  held  until  the  State  of 
Massachusetts  ceased  its  appropriations,  in  the  year  1900. 

CIRCUMSTANCES  WHICH  BROUGHT  ABOUT  THE  ACTUAL  BEGIN- 
NING OF  THE  WORK. 

During  the  five  years  that  elapsed  before  the  State  again  began  to 
appropriate  money  for  the  suppression  of  the  gipsy  moth  and  the 
blown-tail  moth,  as  is  well  known,  the  gipsy  moth  spread  from  a 
restricted  territory  of  :;.V.)  square  miles  throughout  an  extended  range 
of  2:22\  square  miles  and  even  more.  As  soon  as  the  effort  to  exter- 
minate it  was  abandoned,  owinjj  to  the  lapse  of  the  appropriations 
for  the  year  loot),  the  project  of  Importing  parasites  was  taken  up 
by  the  Chief  of  the  Bureau  of  Entomology,  who  be^an  correspond- 
ence with  a' number  of  European  entomologists  with  this  end  in  view. 
Especial  efforts  were  made  to  import  the  Calosomas,  but  failed, 

partly  o\vin#  to  a  hick  of  interest  in  the  matter  on  the  part  of  the 

Europeans.  In  L902  Mr.  \V.  B,  AJwood,  entomologist  of  the  Vir- 
ginia Agricultural  Experiment  Station,  went  abroad  for  a  series  of 
months  and  was  requested  by  the  chief  of  the  entomological  service 
of  the  l/nited  States  Depart  incut  of  Agriculture  to  endeavor  to  find, 
in  some  well-placed  situation  in  Europe,  one  or  more  competent  col- 
lectors of  insects  who  would  undertake  systematically  to  send  gipsy- 
moth  parasites  to  America.  This  effort  also  failed,  and  Mr.  Alwood 
was  unable  to  find  the  proper  persons.  Finally,  in  December,  1904, 
Congress  was  asked  to  make  a  small  appropriation  for  the  distinct 
purpose  of  attempting  the  importation  of  these  parasites,  and  the 
sum  of  $2,500  was  appropriated  for  this  purpose  in  the  session  of  the 
winter  of  1904-5.  During  the  corresponding  session  of  the  Massa- 
chusetts State  Legislature,  State  appropriations  began  once  more.  In 
1904  it  was  apparent  to  everyone  that  the  old  areas  had  become 
reinfested  and  that  the  insect  had  spread  widely.  Private  estates 
and  woodlands  in  June  and  July  of  that  year  were  almost  completely 
defoliated.     Kirkhind  wrote: 

From  Belmont  to  Saugus  and  Lynn  a  continuous  chain  of  woodland  colonies  pre- 
sented a  sight  at  once  disgusting  and  pitiful.  The  hungry  caterpillars  of  both  species 
of  moths  swarmed  everywhere;  they  dropped  on  persons,  carriages,  cars,  and  auto- 
mobiles, and  were  thus  widely  scattered.    They  invaded  houses,  swarmed  into  living 

95G770— Bull.  Ul— 11  1 


50 


PARASITES  OF  GIPSY  AND  BROWN -TAIL  MOTHS. 


and  sleeping  rooms,  and  even  made  homes  uninhabitable  *  *  *.  Real  estate  in 
the  worst-infested  districts  underwent  a  notable  depreciation  in  value.  Worst  of  all, 
pines  and  other  conifers — altogether  too  scarce  in  eastern  Massachusetts — were  killed 
outright  by  the  gipsy-moth  caterpillars,  while  shade  trees  and  orchards  were  swept 
bare  of  foliage. 

There  was  a  general  demand  upon  the  State  legislature  and  an 
excellent  bill  was  prepared  and  passed  with  the  appropriation  of 
$300,000,  $75,000  to  be  expended  during  1905,  $150,000  and  any 
unexpended  balance  during  1906,  and  $75,000  and  any  unexpended 
balance  during  1907,  up  to  May  1,  1907,  inclusive.  And  to  this 
appropriation  there  was  added  the  clause  "for  the  purpose  of  experi- 
menting with  natural  enemies  for  destroying  the  moths,  $10,000 
is  additionally  appropriated  for  each  of  the  years  1905,  1906,  and 
1907."  There  was  then  available  in  the  spring  of  1905  the  appro- 
priation of  $2,500  by  the  General  Government  and  that  of  $10,000 
by  the  State  of  Massachusetts  for  work  with  the  natural  enemies. 
Mr.  A.  H.  Kirkland  was  appointed  superintendent  for  suppressing 
the  gipsy  and  brown-tail  moths,  by  Gov.  Douglas,  and  immediately 
following  his  appointment,  and  with  the  approval  of  his  excellency 
the  governor,  went  to  Washington,  and  by  arrangement  with  the 
honorable  the  Secretary  of  Agriculture,  Mr.  James  Wilson,  arranged  a 
cooperation  between  the  State  and  the  Department  of  Agriculture 
whereby  the  Chief  of  the  Bureau  of  Entomology  of  the  department 
was  practically  placed  in  charge  of  the  details  of  the  attempt  to  import 
parasites  from  abroad,  in  consultation  with  Mr.  Kirkland. 

The  reasons  which  influenced  Mr.  Kirkland  in  entering  into  this 
cooperation  between  the  State  and  the  United  States  Department  of 
Agriculture  were  expressed  in  his  first  annual  report  (p.  117). 

At  this  time  for  more  than  25  years  the  chief  of  the  bureau  had 
been  devoting  his  especial  efforts  to  the  study  of  the  parasitic  Hymen- 
opt  era,  and  had  especially  interested  himself  in  the  subject  of  their 
biology  and  host  relations.  He  had  accumulated  a  card  catalogue 
of  more  than  20,000  entries  of  records  of  the  specific  relations  of 
parasites  to  specific  insects,  the  great  majority  of  these  being  Euro- 
pean records  and  covering  all  of  the  published  information  regarding 
the  parasites  of  the  gipsy  moth  and  the  brown-tail  moth.  He  also 
had  the  advantage  of  the  personal  acquaintance  of  most  of  the 
European  entomologists  interested  in  this  kind  of  work.  These 
facts  were  known  to  Mr.  Kirkland  and  caused  his  action. 

AN  INVESTIGATION  OF  THE  INTRODUCTION  WORK. 

From  the  beginning  of  the  work,  and  even  before,  certain  citizens 
of  Boston,  impressed  by  l  he  claims  of  I  he  State  Board  of  I  iori  [culture 
<>f  California  as  to  the  results  said  to  have  been  achieved  by  the 
agents  of  the  board  in  the  introduction  of  beneficial  insects,  urged 


INVESTIGATION  OF  INTRODUCTION  WORK. 


51 


the  employment  of  these  agents  in  the  work  of  introducing  the  para- 
sites of  the  gipsy  moth  and  brown-tail  moth.  The  arguments  in 
favor  of  this  proposal  were  duly  considered  by  the  superintendent 
of  the  Massachusetts  work,  who  decided  for  many  reasons  to  con- 
duct the  introduction  experiments  along  the  lines  just  described 
and  not  to  call  in  the  assistance  of  the  California  people.  In  his 
third  report,  submitted  January  1.  190S,  Mr.  Kirkland  expressed 
the  situation  as  follows: 

In  spite  of  all  the  thought,  energy,  and  skill  that  have  been  brought  to  bear  on  this 
mail  important  problem  of  introducing  the  natural  enemies  of  the  moths — a  problem 
entirely  novel  in  the  field  of  entomology  it  was  apparent  during  the  winter  of  1906-7 
I  hat  several  of  our  influential  citizens  had  expected  immediate  results  from  the 
importation  of  the  parasites,  and  were  beginning  to  get  restive  because  such  results 
had  not  been  obtained.  Several  expressed  a  doubt  if  everything  possible  was  being 
done  to  secure  the  successful  introduction  of  the  parasites.  Others  became  enthusi- 
astic over  the  specious  proposition  pot  forward  by  a  certain  western  horticulturist 
(not  an  entomologist^,  who  offered  to  suppress  the  gipsy  moth  in  Massachusetts  by 
means  of  parasites  for  the  sum  of  $25. 0(H).  "im  cur.',  no  pay."  This  state  of  affairs 
was  no  doubt  a  natural  outcome  of  the  desire  to  avoid  a  repetition  of  the  great  damage 
to  property  caused  by  the  moth  in  past  years.  Again,  men  without  any  technical 
knowledge  of  entomology  or  of  the  life  histories  of  the  parasites,  not  realizing  the  difli- 
culties  in  securing,  shipping,  breeding,  and  disseminating  these  beneficial  insects, 
and  equally  ignorant  of  how  long  it  takes  an  imported  insect  to  become  established 
even  under  the  most  favorable  conditions,  might  well  be  pardoned  for  expecting 
almost  immediate  results  from  the  introduction  of  the  relatively  small  number  of 
parasites—small  indeed  in  comparison  with  the  tremendous  numbers  of  the  moths. 

Coming  before  the  legislature  during  the  session  of  1906-7,  this 
group  of  Boston  citizens  stated  thai  it  was  their  opinion  that  the 
work  with  parasites  was  not  progressing  with  sufficient  rapidity,  and 
asked  the  Legislature  to  appropriate  funds  and  to  instruct  the  super- 
intendent to  secure  additional  counsel  and  advice  in  the  matter  to 
determine  whether  the  work  was  going  on  in  the  right  way.  The 
legislature  agreed  and  appropriated  the  additional  sum  of  SI 5,000  to 
enable  the  superintendent  to  secure  such  advice. 

It  was  firM  suggested  that  he  consult  only  with  certain  California 
men  who  had  had  experience  in  importing  parasites  of  scale  insects. 
He,  however,  considered  that  consultation  with  men  whose  experi- 
ence had  been  confined  to  a  single  group  of  insects,  not  to  the  same 
group  as  the  gipsy  moth  and  the  brown-tail  moth,  while  possibly 
helpful,  would  not  be  broad  enough  to  throw  any  great  light  on 
the  Massachusetts  problem.    To  use  his  own  words — 

It  seemed  much  wiser  and  certainly  more  thoroughgoing,  since  this  entire  work 
might  be  called  in  question  at  any  time,  and  in  view  of  the  large  amount  of  money 
Massachusetts  was  expending  in  securing  parasites,  to  consult  not  with  the  trained 
entomologists  of  a  single  State,  but  with  as  many  entomologists  of  national  or  even 
world-wide  reputation  as  possible.  In  other  words,  that  a  large  number  of  entomolo- 
gists of  the  highest  possible  scientific  standing,  and  particularly  those  having  practical 
experience  in  dealing  with  parasitic  insects,  should  be  invited  to  visit  Massachusetts, 


52 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


learn  of  our  difficult  problems  on  the  spot,  examine  into  the  methods  of  importing, 
rearing,  and  distributing  parasites,  and  then  give  us  the  benefit  of  their  criticism  and 
counsel,  based  on  a  full  knowledge  of  the  facts  at  hand.  He  also  suggested  that, 
since  by  some  this  movement  might  be  taken  as  a  criticism  on  his  management  and 
on  his  judgment  in  placing  the  direction  of  the  work  in  the  hands  of  Dr.  Howard,  it 
would  be  well  to  have  some  outside  board  or  commission  take  charge  of  the  matter, 
so  that  it  should  be  entirely  an  ex  parte  affair,  free  from  any  suggestion  of  influence 
by  the  present  administration  of  the  work.  The  suggestion  to  authorize  the  super- 
intendent to  invite  the  entomologists  was  heartily  indorsed  by  the  legislative  com- 
mittee which  had  the  matter  under  consideration,  while  the  arrangement  of  the  entire 
affair  was  left  in  his  hands. 

In  his  selection  of  experts,  Mr.  Kirkland  was  aided  by  Prof.  C.  H. 
Fernald,  of  the  Massachusetts  Agricultural  Experiment  Station, 
one  of  the  oldest  and  best  posted  entomologists  in  the  country;  and 
Mr.  Kirkland  himself,  it  must  be  remembered,  had  been  engaged  in 
active  entomological  work  for  15  }rears  and  had  held  official  posi- 
tions in  the  Association  of  Economic  Entomologists,  thus  having  a  • 
very  broad  personal  acquaintance  with  the  best  workers.  The  list 
selected,  as  quoted  from  Mr.  Kirkland's  report,  was  as  follows: 

Prof.  Edward  M.  Ehrhorn,  deputy  commissioner  of  horticulture,  State  of  California, 
a  man  of  large  practical  experience  in  importing,  breeding,  and  disseminating  insect 
parasites,  particularly  those  of  scale  insects,  and  also  a  man  well  trained  in  applied 
entomology. 

Prof.  Herbert  Osborn,  Ohio  State  University,  one  of  the  country's  best  known 
teachers  of  entomology,  and  of  large  experience  in  investigation  and  laboratory  work. 

Dr.  John  B.  Smith,  entomologist.  New  Jersey  Agricultural  Experiment  Station, 
an  investigator  of  the  highest  order,  a  successful  teacher,  and  the  author  of  numerous 
standard  works  on  insects. 

Prof.  S.  A.  Forbes,  State  entomologist,  Illinois,  a  most  successful  teacher  and  investi- 
gator, and  one  of  the  most  prominent  entomologists  of  the  Middle  West. 

Prof.  E.  P.  Felt,  State  entomologist  of  New  York,  a  well-known  writer  on  and  investi- 
gator of  insect  pests,  and  particularly  ingenious  in  devising  laboratory  methods. 

Prof.  H.  A.  Morgan,  director  of  the  Tennessee  Agricultural  Experiment  Station, 
of  large  experience,  and  one  of  the  best-known  entomologists  of  the  Southern  States. 

Prof.  M.  V.  Slingerland,  Cornell  University,  New  York,  an  investigator  with  hardly 
an  equal,  and  one  who  has  had  great  success  in  studying  life  histories  of  beneficial 
and  injurious  insects. 

In  addition  to  these,  the  following  well-known  foreign  entomolo- 
gist ^,  visiting  Boston,  wore  asked  to  investigate  the  situation  care- 
fully, to  study  the  laboratory  and  held  methods,  and  to  report: 

Prof.  Charles  P.  Lounsbury,  entomologist,  Cape  Town,  South  Africa,  one  who  has 
had  great  experience  as  well  as  great  success  in  importing  beneficial  insects. 

Prof.  Walter  W.  Froggatt,  government  entomologist,  New  South  Wales,  and  also 
investigator  for  Victoria  and  Queensland.  Prof.  Froggatt's  work  has  boon  practi- 
cally along  the  same  line  as  that  of  Prof.  Lounsbury,  and  has  met  with  a  large  measure 
of  success. 

Dr.  James  Fletcher,  dominion  entomologist,  Canada,  well  known  for  his  success  in' 
working  out  difficult  points  in  tlx-  life  histories  of  insects,  and  more  particularly  in 
dealing  w  ith  a  wide  range  of  injurious  species. 

Prof.  R.  Blanchard,  University  of  Paris,  and  member  of  the  Academy  of  Medicine. 

i)r.  (i.  Horvath,  director  of  zoological  section,  National  Hungarian  Museum,  mem- 


IXVKSTTGATIOX  OF  INTRODUCTION  WORK. 


53 


ber  of  the  Academy  of  Science  of  Hungary  and  formerly  director  of  the  entomological 
station  of  Hungary.    The  last  two  gentlemen  are  entirely  familiar  with  the  two  moths  % 
and  their  parasites. 

Dr.  Richard  Heymons,  extraordinary  honorary  professor  and  custodian  at  the  Zoo- 
logical Museum  of  the  Royal  Institute  of  Berlin.  Dr.  Heymons  has  made  a  large 
-Judy  of  the  injurious  insects  of  central  Europe,  and  particularly  of  their  natural 
enemies. 

Prof.  A.  Beverin,  conservator  at  the  Royal  Museum  of  Natural  History  of  Belgium, 
and  member  of  the  Superior  Council  of  Forests.  Frof.  Severin's  position  is  naturally 
thai  of  one  of  the  1><  «1  posted  entomologists,  particularly  with  reference  to  dangerous 
forest  insects. 

hi  addition  to  those  foreign  entomologists.  Prof.  Filippo  Silvestri, 
of  the  Royal  Agricultural  School  of  Portici,  Italy,  visiting  America 
on  an  official  mission  in  the  summer  of  1908,  visited  Boston,  and 
was  asked  to  give  his  professional  opinion  of  the  work,  his  report 
being  printed  in  the  fourth  annual  report  of  the  superintendent, 
issued  January,  1909,  by  L.  II.  Worthley,  acting  superintendent. 

It  is  worthy  of  note  that  Prof.  Silvestri  had  been  commissioned  by 
the  K.  Aecademia  dei  Lineei  and  by  the  royal  Diinister  of  agriculture 
of  Italy  to  investigate  the  work  in  economic  entomology  being  done 
in  the  lnited  State-,  and  had  visited  all  portions  of  the  country, 
including  California  and  Hawaii.  Btudying  with  especial  care  all  the 
work  being  done  with  parasites.  It  should  he  pointed  out  also  that 
the  California  claims  were  perfectly  well  understood  by  all  of  the 
American  experts,  Mr.  Ehrhorn  himself  being  the  second  ranking 
officer  in  the  California  service,  and  the  others  having  either  visited 
California  partly  for  the  purpose  of  investigating  this  work,  or  being 
perfectly  familiar  with  the  situation  by'study  of  the  publications  and 
by  correspondence.  Moreover,  of  the  foreign  experts,  Mr.  Froggatt 
had  just  come  from  California  on  an  investigating  trip  for  the  gov- 
ernment of  the  Federated  Colonies  of  Australia  which  subsequently 
carried  him  around  the  world,  Mr.  Lounsbury  had  visited  California 
for  the  purpose  of  studying  this  work,  and  Dr.  Fletcher  had  repeat- 
edly visited  that  State. 

The  report8  of  all  of  these  expert-,  with  the  exception  of  that  of 
Prof.  Silvestri,  are  published  in  the  third  annual  repoi  t  of  the  Massa- 
chusetts superintendent,  Boston,  P.Mis,  Prof.  Silvestri's  report  being 
published,  as  above  stated,  in  the  fourth  annual  report  of  the  super- 
intendent. • 

It  will  be  entirely  unnecessary  to  quote  from  these  reports,  since 
they  may  be  found  in  full  in  the  State  documents  mentioned.  It 
will  suffice  to  state  that  the  work  was  commended,  it  is  safe  to  say, 
with  enthusiasm  by  every  individual.  Specific  consideration  was 
given  to  the  California  suggestion  by  Mr.  Lounsbury,  by  Mr.  Frog- 
gatt, and  by  Prof.  Slingerland.  Suggestions  were  made  by  several 
of  them  that  the  study  of  the  fungous,  bacterial,  and  protozoan 
diseases  of  the  larva1  should  be  taken  up.    Dr.  Felt  and  Dr.  Smith 


54 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


recommended  the  importance  of  the  introduction  of  the  Japanese 
•  parasites,  and  Dr.  Felt  suggested  the  importance  of  careful  biolog- 
ical studies  of  the  parasites,  not  only  in  America  but  in  Europe.  All 
of  these  suggestions  coincided  with  plans  already  made  which  were 
about  to  be  entered  upon,  as  indicated  in  following  pages. 

The  subject  of  the  study  of  the  diseases  of  the  caterpillars  does  not 
come  under  the  range  of  the  present  bulletin,  but  since  it  has  been 
mentioned,  it  should  be  stated  that  the  State  superintendent  has  for 
the  past  two  years  been  having  this  subject  investigated  and  that  it 
is  now  going  on  under  the  expert  supervision  of  Dr.  Roland  Thaxter, 
of  Harvard  University,  and  Dr.  Theobald  Smith,  of  the  Harvard 
Medical  School. 

Mr.  Kirkland's  summary  seems  fully  justified.    It  is  as  follows: 

It  will  be  seen  from  the  foregoing  that  the  work  of  importing  parasites  of  the  gipsy 
and  brown-tail  moths  in  Massachusetts  has  been  thoroughly  examined  by  practically 
a  congress  of  the  world's  leading  entomological  experts.  And  it  is  believed  that  their 
consensus  of  opinion,  which  is,  in  the  main,  that  everything  possible  to  secure  the 
successful  importation  of  these  insects  is  being  done,  will  be  taken  as  authoritative 
and  final.  It  would  seem  that  the  last  word  has  been  said  on  this  matter,  and  that 
there  should  be  no  further  occasion  for  that  kind  of  adverse  criticism,  whose  sole 
effect  is  to  harass  those  who  are  giving  their  best  thought  and  most  sincere  effort  to  the 
accomplishment  of  the  desired  result.  Destructive  criticism  of  scientific,  work,  by 
the  amateur  or  dilettante,  is  absolutely  valueless.  Constructive  criticism,  such  as 
these  reports  make  on  certain  minor  details  of  this  important  work,  is  helpful  and  a 
public  good. 

NARRATIVE  OF  THE  PROGRESS  OF  THE  WORK. 

Down  to  the  time  when  this  work  was  begun,  all  attempts  at  the 
international  handling  of  beneficial  insects  had  been  done  either  by 
correspondence  or  by  the  sending  of  an  individual  collector  to  search 
for  such  insects  and  to  forward  them  by  mail  or  express  or  to  bring 
them  back  himself  in  comparatively  small  numbers,  the  beneficial 
species  being  either  at  ones  liberated  in  the  field  or  reared  for  a  lime 
in  confinement  and  then  liberated.  In  planning  the  present  work 
the  normal  geographic  ranges  of  both  the  gipsy  motli  and  the  brown- 
1  nil  moth  were  well  known  and  most  of  their  parasites  had  been  listed, 
so  that  the  problem  seemed  to  be  a  comparatively  simple  one.  Owing 
to  the  fact  that  the  most  abundant  of  the  Japanese  gipsy  moths  (four 
of  them  are  listed)  presents  rather  marked  differences  from  the  Euro- 
pean and  New  England  form — so  much  so,  in  fact,  as  almost  to  justify 
the  opinion  that  it  is  a  distinct  species — and  as  the  ancestors  of  the 
New  England  gipsy  moth  came  from  Europe,  it  was  decided  to  con- 
centrate l he  effort,  for  a  time  at  least  and  in  the  main,  upon  Euro- 
pean parasites  and  natural  enemies.  From  the  outset  the  idea  was 
to  secure  as  many  parasites  belonging  to  as  many  different  species  as 
possible  Prom  all  parts  of  Europe,  in  the  hope  of  establishing  in  New 
England  approximately  the  natural  environment  of  the  gipsy  moth 


NARRATIVE  OF  PROGRESS  OF  WORK. 


55 


nnd  the  brown-tail  moth  in  so  far  as  their  natural  checks  are  con- 
cerned. It  was  the  aim  to  establish,  not  one  or  half  a  dozen  of  its 
natural  enemies,  but  all  of  them,  aiming  at  the  same  time  to  avoid 
the  introduction  of  hyporparasites — that  is,  those  species  that  prey 
upon  the  true  parasites  of  the  injurious  forms — thus,  if  possible,  bring- 
ing about  an  even  more  favorable  situation  for  the  primary  parasites 
in  New  England  than  exists  in  Europe. 

On  account  of  the  enormous  numbers  in  which  both  gipsy  and 
brown-tail  moths  existed  in  Massachusetts,  it  was  considered  that 
the  simplest  way  to  secure  the  true  European  parasites  was  to 
collect  caterpillars  and  chrysalids  wherever  they  could  be  found 
in  Europe,  box  them,  and  ship  them  directly  to  Boston;  this  always 
with  the  certainty  that  a  certain  percentage,  high  or  low,  would 
contain  living  parasites  which  would  probably  issue  in  the  adult 
condition  on  the  journey  or  after  arrival  in  America,  in  which  event 
they  could  be  cared  for,  reared  until  sufficiently  multiplied,  and  then 

liberated. 

A  temporary  laboratory  for  the  receipt  and  care  of  specimens 
was  immediately  established  by  Mr.  Kirkland  at  Maiden.  Mass., 
and  a  careful  search  was  begun  for  a  suitable  location  for  a  perma- 
nent laboratory  for  the  care  of  parasites.  It  was  considered  desirable 
that  this  laboratory  should  be  placed  in  a  region  in  which  both  the 
gipsy  moth  and  the  brown-tail  moth  occurred  in  abundance,  so 
thai  there  might  be  plenty  of  material  for  food  for  the  parasites 
at  all  times:  and  it  was  also  considered  of  importance  that  a  con- 
siderable area  of  land  should  be  secured  which  could  be  controlled 
for  outdoor  experiments.  Mr.  Kirkland  finally  found  a  small  farm 
with  buildings  in  North  Saugus,  the  location  easily  accessible  by 
elect  l  ie  cars  and  sufficiently  isolated.  (See  PI.  II,  fig.  1.)  The 
house  was  large  enough  to  give  ample  room  for  laboratory  use, 
and  at  tin1  same  time  furnished  dwelling  rooms  for  the  state  official 
in  charge.  In  the  immediate  vicinity  there  was  a  chain  of  large 
woodland  colonies  of  the  gipsy  moth  and  numerous  orchards  infested 
by  the  brown-tail  moth,  as  well  as  a  large  area  of  scrub-oak  land 
where  the  brown-tail  moth  occurred  very  abundantly.  A  portion 
of  the  building  occupied  as  a  laboratory  was  fitted  up  by  the  State 
with  shelves,  tables,  rearing  cages,  and  all  necessary  apparatus 
and  supplies,  and  the  State  employed  Mr.  F.  H.  Mosher,  with  Mr. 
E.  A.  Back  and  Mr.  ().  L.  Clark  as  assistants,  to  help  care  for  the 
parasites. 

While,  as  just  stated  and  for  the  reasons  given,  the  main  effort 
was  made  with  Europe,  correspondence  was  begun  with  the  Imperial 
Agricultural  Experiment  Station  at  Nishigahara,  Tokyo,  Japan, 
and  the  Imperial  Agricultural  College  at  Sapporo,  in  order  to  secure; 
if  possible,  the  services  of  expert  Japanese  entomologists  in  sending 


56  PAEASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

Japanese  parasites,  and  Prof.  S.  I.  Kuwana  immediately  prepared 
an  important  sending,  which,  however,  was  not  productive,  through 
accidents  in  transportation.  The  method  tried  by  Prof.  Kuwana 
was  interesting.  A  small  tree  carrying  a  number  of  infested  gipsy- 
moth  caterpillars  was  packed  in  a  large  wooden  case  with  wire- 
gauze  sides;  another  case  of  small  elms  was  shipped' with  the  insects, 
and  they  were  thus  supplied  with  fresh  food  from  time  to  time  as 
far  as  Hawaii.  The  case,  however,  shrunk  in  transit,  making  open- 
ings through  which  the  parasites  for  the  most  part  escaped. 

In  May,  1905,  the  Chief  of  the  Bureau  of  Entomology  visited 
Boston  for  conference  with  Mr.  Kirkland,  and  on  June  3  sailed 
from  Boston  to  Naples.  Landing  in  Naples  on  June  13,  he  at  once 
proceeded  to  the  Royal  Agricultural  School  at  Portici,  some  miles 
away,  and  held  a  conference  with  Prof.  F.  Silvestri,  the  entomologist 
of  the  college,  and  his  principal  assistant,  Dr.  G.  Leonardi.  By 
good  fortune,  Prof.  Silvestri  was  able  to  point  out  a  locality  in 
Sardinia  where,  during  1904,  there  had  been  a  severe  outbreak  of 
the  gipsy  moth  and  where,  therefore,  during  1905  parasites  could 
with  almost  absolute  certainty  be  predicted  to  occur  in  numbers. 
With  true  scientific  enthusiasm,  both  Prof.  Silvestri  and  Dr.  Leonardi 
volunteered  their  assistance,  and  Dr.  Leonardi  was  at  once  com- 
missioned by  his  chief  to  proceed  to  Sardinia  and  to  collect  such 
caterpillars  as  he  could  find  and  forward  them  in  tight  wooden 
boxes,  with  a  supply  of  food,  to  Boston.  His  expedition  was  a 
success,  and  there  were  received  from  him  at  Boston,  on  the  15th 
of  July,  7  boxes,  on  the  26th  of  July  24  boxes,  and  on  the  1st  of 
August  7  boxes,  all  containing  valuable  material,  the  most  important 
being  a  large  series  of  living  puparia  of  certain  parasitic  tachina 
(lies. 

This  extremely  cordial  and  profitable  reception  at  Portici  by 
Prof.  Silvestri  and  Dr.  Leonardi,  both  personally  known  to  the 
chief  of  the  bureau  from  former  visits,  was  but  a  foretaste  of  the 
encouragement  which  was  to  be  met  at  all  points,  and  it  may  very 
properly  be  said  in  advance  that  throughout  the  whole  of  the  work 
many  European  and  Japanese  entomologists,  both  officials  and 
private  individuals,  have  shown  an  extreme  liberality  in  their  offers 
of  assistance  in  this  great  piece  of  experimental  work,  and  the  State 
of  Massachusetts  and  the  United  States  Government  are  under 
great  obligations  to  them  for  their  help  and  encouragement.  For 
the  work  done  by  Dr.  Leonardi,  just  described,  and  for  similar 
work  done  in  ensuing  years,  with  Prof.  Silvestri's  permission,  no 
compensation  would  be  accepted,  and  the  State  of  Massachusetts 
has  paid  simply  for  (lie  expenses,  such  as  packing,  postage,  small 
traveling  expenses,  and  items  of  that  general  character. 


Bui.  91,  Bureau  of  Entomo1og7,  U.  S.  Dept.  of  Agriculture. 


Plate  II. 


Fig.  1.— View  of  Parasite  Laboratory  at  North  Sauqus,  Mass.    Original.  I 


Fig.  2.— View  of  Parasite  Laboratory  at  Melrose  Highlands,  Mass.  (Original.) 


NARRATIVE  OF  PROGRESS  OF  WORK. 


57 


After  Portici,  Florence  was  visited,  where  a  conference  was  held 
with  Prof.  A.  Berlese,  of  the  Royal  Station  of  Agricultural  Ento- 
mology, and  his  assistants  Drs.  Del  Guercio  and  Ribaga.  It  seemed 
that  no  occurrences  of  either  the  gipsy  moth  or  the  brown-tail  moth 
were  known  that  season  in  Tuscany  or  adjoining  portions  of  Italy. 
Prof.  Berlese  spoke  of  the  destruction  of  an  outbreak  of  the  gipsy 
moth,  in  southern  Italy  some  years  previously  by  a  disease  which 
he  considered  to  be  identical  with  the  pebrine  of  the  domestic  silk- 
worm. He  promised  to  keep  up  a  watch  for  occurrences  of  the 
pests  and  wherever  possible  to  assist  in  the  introduction  of  parasites. 
A  few  days  were  then  spent  in  Lombard  y,  searching  for  the  larva? 
of  either  of  the  injurious  species,  but  without  success.  Then,  pro- 
ceeding to  Vienna,  the  celebrated  Natural  History  Museum  was 
visited  and  the  well-known  curator  of  Lepidoptera,  Dr.  Hans 
Rebel,  was  interviewed.  Dr.  Rebel  stated  that  both  the  gipsy 
moth  and  the  brown-tail  moth  were  to  be  found  rather  commonly 
in  parts  of  Austria,  and  it  was  decided  to  employ  a  professional 
collector  to  assist  in  the  work  of  shipping  larva1  to  Boston.  1'pon 
Dr.  Rebel's  recommendation,  Mi*.  Kritz  Wagner  was  employed. 
Mr.  Wagner  was  and  is  a  resident  of  Vienna,  is  well  versed  in  the 
subject  <>f  European  butterflies  and  moths,  aud  perfectly  familiar 
with  all  the  best  collecting  places  for  many  miles  about  Vienna. 
Mr.  Wagner  accompanied  the  writer  on  several  expeditions.  The 
first  trip  was  taken  to  the  suburbs  of  Vienna,  and  there  the  first 
European  specimen  of  the  gipsy-moth  larva  was  found.  It  was 
resting  on  the  trunk  of  a  locust  tree  by  the  side  of  the  street,  and 
further  examination  showed  that  there  were  a  hundred  or  more 
caterpillars  on  the  trunk  and  limbs  of  the  same  tree.  There  was 
some  evidence  of  parasitism,  and  the  white  cocoons  of  a  microgaster 
parasite  ( A /><i  nt>  l<  s  fulvipes  Hal.)  were  found  here  add  there  in 
the  crevices  of  the  bark.  This  particular  tree  ami  another  one, 
to  be  mentioned  later,  indicate  very  well  the  condition  of  the  gipsy 
moth  in  Europe.  A  hundred  nearly  full-grown  larva-  were  present, 
but  there  w  is  hardly  any  evidence  of  defoliation.  A  trained  ento- 
mologist walking  by  the  tree  would  not  have  noticed  that  insects 
had  been  feeding  upon  it  to  any  serious  extent.  On  the  other 
hand,  a  similar  tree  in  any  of  the  small  towns  about  Boston  would 
have  carried  not  100  larva?,  but  probably  some  thousands,  and  at 
that  time  of  the  year  would  hardly  have  had  a  whole  leaf.  These 
specimens  were  collected  and  sent  to  Boston. 

Later  a  trip  was  taken  into  tho  country  to  the  battlefield  of  Wa- 
gram,  and  here  on  two  roadside  poplars  was  found  another  colony  of 
the  caterpillars  ranging  in  size  from  the  second  stage  to  full-grown 
larva?.    There  was  here  more  extensive  evidence  of  parasitism  by 


58 


PARASITES  OF  GIPSY  AND  BROWX-TAIL  MOTHS. 


microgaster  parasites.  Their  white  cocoons  were  found  abundantly, 
and  here  again,  although  there  must  have  been  250  or  more  larvae  on 
the  trees,  the  evidences  of  defoliation  were  very  slight — so  much  so 
that  at  a  rather  short  distance  the  trees  appeared  in  full  leaf.  Dur- 
ing the  remainder  of  June  and  July  Mr.  Wagner  continued  the  search 
and  sent  considerable  material  to  Mr.  Kirkland,  at  Boston. 

After  Vienna,  the  city  of  Budapest  was  visited.  At  the  Natural 
History  Museum  in  that  city  Dr.  G.  Horvath,  the  well-known  director, 
and  Prof.  Alexander  Mocsary  were  consulted,  Prof.  Mocsary  being  one 
of  the  first  authorities  in  Europe  on  the  subject  of  parasitic  Hymen- 
optera.  Neither  of  these  gentlemen,  however,  was  able  to  give  any 
new  points  in  connection  with  the  parasites  of  the  gipsy  moth  and 
the  brown-tail  moth.  The  agricultural  experiment  station  in  the  sub- 
urbs of  Pesth  was  then  visited,  and  Prof.  Josef  Jablonowski,  the 
entomologist  of  the  station,  was  consulted."  By  this  time  it  was 
the  4th  of  July,  and  already  the  season  in  Hungary  was  far  advanced, 
being  about  two  weeks  or  more  earlier  there  than  at  Vienna.  Prof. 
Jablonowski  stated  that  gipsy  moths  had  been  found  in  certain 
localities  in  Transylvania,  but  that  the  adults  were  already  issuing 
and  that  the  brown-tail  moths  had  been  flying  for  some  time.  He 
exhibited,  however,  a  large  box  full  of  the  previous  winter's  nests 
of  brown-tail  larvae,  and  stated  that  in  the  early  spring  he  had 
reared  from  these  nests  many  hundreds  of  parasitic  insects.  This  at 
once  seemed  to  indicate  a  very  easy  way  of  importing  such  parasites, 
since  these  nests  could  be  readily  collected  in  the  winter  in  large 
numbers  and  sent  to  Boston  in  great  packages — a  bushel  or  more  in 
each  package — in  the  late  fall  or  winter  season,  and  Prof.  Jablonowski 
volunteered  to  make  every  effort  the  following  winter  to  send  over 
a  large  quantity.  Taking  into  consideration  the  small  size  of  the 
brown-tail  moth  caterpillars  during  hibernation,  it  seemed  very 
strange  that  they  should  be  so  extensively  parasitized  as  indicated 
by  Jablonowski.  The  larger  caterpillars  in  the  late  spring  and  early 
summer  would  seem  to'  be  much  more  likely  to  be  extensively  infested. 
These  winter  nests,  remaining  alone  on  the  trees  after  the  leaves  have 
fallen,  would  seem  to  be  an  attractive  place  for  small  Hymenoptera 
of  various  kinds,  in  which  they  might  seek  shelter  for  hibernation,  and, 
while  of  course  there  was  a  chance  that  some  of  the  true  parasites  of 
later  stages  might  thus  be  sheltered,  it  was  with  considerable  doubts 
as  to  the  ultimate  result  that  the  writer  arranged  for  the  importation 
of  these  nests  in  large  quantity.  Even  if  unsuccessful,  however,  it 
seemed  that  the  experiment  must  be  tried. 

From  Budapest,  Dresden  was  reached,  and,  as  in  Vienna  and 
Budapest,  the-  principal  museum  (the  Zoological  Ethnological 
Museum)  was  at  once  visited.  Dr.  K.  M.  Heller,  at  that  time  acting 
director  of  the  museum,  was  asked  to  recommend  a  good  man  who 


NARRATIVE  OF  PROGRESS  OF  WORK. 


59 


might  be  employed  a<  a  professional  collector  to  undertake  work  in 
the  same  manner  as  that  done  by  Fritz  Wagner  in  Vienna.  Dr. 
Heller  recommended  Mr.  Edward  Schopfer,  who  was  at  once  engaged. 
Although  at  the  date  of  the  first  visit  to  him  the  sea><>n  was  already 
considerably  advanced  (July  7),  Mr.  Schopfer  had  rearing  cages  in 
operation  in  his  rooms,  and  in  these  cages  were  a  number  of  nearly 
fall-grown  larva'  of  the  gipsy  moth.  lie  knew  the  localities  about 
Dresden  where  these  insects  were  to  be  found,  and  at  once  began 
sending  specimens  to  Boston.  The  well-known  Forest  Academy  at 
Tharaiidt.  near  Dresden,  was  visited,  and  Prof.  Arnold  Jacobi  and  his 
assistant,  Mr.  W.  Barf,  were  interested  and  promised  assistance, 
especially  in  the  matter  of  sending  specimens  of  ( '<i(<>xn,,t<i  sycophanta 
(see  PI.  I,  frontispiece)  and  C.  unju'isttor.  Other  trips  were  made 
in  the  vicinity  of  Dresden,  and  then  the  journey  was  resumed  to 
Zurich,  where,  through  the  kindness  of  Dr.  Herbert  Ilaviland  Field, 
director  of  the  Concilium  Bibliographicuin  Zoologieum,  the  writer 
met  Miss  Marie  EU&hl,  editor  of  the  Societas  Entomologica.  a  very 
well-posted  entomologist,  especially  on  matters  relating  to  Lepidop- 
tera,  who  had  and  has  a  large  correspondence  throughout  northern 
Germany.  She  was  engaged  as  the  official  agent  of  the  investigation 
for  that  part  of  Germany  and  was  able,  through  her  own  work  and  that 
of  her  correspondents,  t«>  -end  a  large  amount  of  material  to  Boston 
before  the  close  of  the  sejison  of  \\H)"y,  and  has  since  continued  the 
work. 

From  Zurich  the  trip  was  resumed  to  Paris,  where  some  time  W8S 
spent  in  interviewing  Dr.  Paul  Marchal.  the  entomologist  of  the 
agricultural  school  conducted  under  the  mini-try  of  agriculture,  and 
other  entomologists,  and  in  visiting  the  scientific  societies  for  the  pur- 
pose of  interesting  naturalists  in  the  work.  Many  trips  were  taken 
to  towns  around  Paris  in  search  of  the  pupa?  of  the  gipsy  moth  and  to 
visit  local  collectors  in  search  of  information,  after  which  the  return 
journey  was  made  to  America. 

The  result  of  this  initial  trip  was  to  demonstrate  that  it  is  an  easy 
mattei  and  a  comparatively  inexpensive  one  to  import  certain  of  the 
parasites  of  both  the  gipsy  moth  and  the  brown-tail  moth  in  living 
condition  into  the  United  States.  The  most  important  part  of  the 
European  range  of  the  two  species  was  visited,  and  the  entomologists 
were  organized  into  an  active  body  of  assistants. 

Mention  has  already  been  made  of  the  number  of  boxes  sent  in  by 
Dr.  Leonardi  from  Sardinia.  Ten  boxes  were  shipped  by  Fritz  Wag- 
ner from  Vienna,  47  boxes  from  Schopfer  in  Dresden,  and  3G  from 
Miss  Ivuhl  in  Zurich,  all  of  these  containing  parasitized  larva*  or  pupae 
of  the  gipsy  moth  or  brown-tail  moth. 

Acting  upon  Prof.  Jablonowski's  observations  concerning  the 
existence  of  parasites  in  the  wintering  nests  of  the  brown-tail  moth, 


60 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


arrangements  were  made  with  Miss  Ruhl,  Mr.  Schopfer,  Prof.  A.  J. 
Cook,  who  was  then  in  Berlin,  and  several  volunteer  collectors  to  send 
in  numbers  of  the  winter  nests.  During  his  visit  to  Paris  in  July,  the 
chief  of  the  bureau  had  addressed  a  meeting  of  the  Entomological 
Society  of  France  on  the  subject  of  Ins  mission  and  asked  the  members 
of  the  society  to  assist  in  the  work.  The  most  remarkable  response  to 
this  request  came  from  Mr.  Eene  Oberthur,  of  Rennes,  who,  although 
not  present  at  the  meeting,  read  the  account  in  the  bulletin  of  the 
society,  and  placed  himself  and  his  services  entirely  at  the  disposal 
of  the  United  States  authorities.  During  the  autumn  of  1905  and 
the  winter  of  1905-6  he  sent  to  Boston  more  than  10,000  winter 
nests  of  the  brown-tail  moth.  In  all,  117,000  nests  were  received 
and  cared  for  during  that  winter. 

In  the  autumn  the  laboratory  house  (PI.  II,  fig.  1,  p.  56)  at  North 
Saugus  was  taken  possession  of  by  Mr.  Kirkland,  fitted  up  as  pre- 
viously described,  and  occupied  by  Mr.  Mosher;  the  parasite  material 
from  Maiden  was  brought  over  and  installed,  and  arrangements  were 
made  for  the  receipt  of  the  brown-tail  winter  nests.  Very  many 
large  boxes  were  constructed,  somewhat  on  the  plan  of  the  Cali- 
fornia parasite-rearing  cage,  each  one  large  enough  to  contain  from  500 
to  1 ,000  nests  of  the  brown-tail  moth,  the  front  being  pierced  with 
auger  holes  in  which  were  inserted  round-bottom  glass  tubes  into 
which  the  emerging  parasites  would  come  in  search  of  light  and 
through  which  they  might  be  examined  to  differentiate  between  the 
primaries  and  the  hyperparasites.  Much  carpenter  work  was  done 
during  the  autumn  and  winter  months  and  on  into  the  spring. 
Double  windows  and  double  doors  were  provided,  and  every  crack 
in  the  laboratory  rooms  was  sealed.  Realizing  that  many  different 
kinds  of  insects  might  emerge  from  tins  large  supply  of  silken  nests, 
including  possibly  species  injurious  to  agriculture  not  previously 
introduced  into  the  United  States,  as  well  as  dangerous  parasites  of 
beneficial  insects,  every  possible  effort  was  made  to  prevent  the  escape 
of  any  insect  whatever  from  the  laboratory  rooms. 

On  account  of  the  importance  of  a  speedy  detection  of  injurious 
forms  coming  from  these  rearing  cages,  and  on  account  of  the 
necessity  for  the  most  expert  supervision  of  the  laboratory  end  of  the 
experiment,  Mr.  E.  S.  G.  Titus,  an  especially  well  trained  expert 
from  the  Bureau  of  Entomology,  was  assigned  in  the  spring  of  1906 
to  the  charge  of  the  laboratory  end  of  the  introduction. 

In  March,  1 900,  Mr.  Titus,  with  the  chief  of  the  bureau  and  with 
Mr.  Kirkland  and  Mr.  Mosher,  visited  the  parasite  laboratory,  and 
for  the  first  time  examined  the  contents  of  the  imported  nests. 
There  were  in  the  different  cages,  well  separated  as  to  localities, 
winter  nests  from  almost  the  whole  <>f  the  European  range  of  the 
brown-tail  moth,  from  Transylvania  on  the  southeast  to  Brittany 


NARRATIVE  OF  PROGRESS  OF  WORK. 


61 


on  the  northwest,  and  from  the  Pyrenees  on  the  southwest  to  the 
shores  of  the  Baltic  on  the  northeast.  In  spite  of  the  voluntary 
assistance  of  such  men  as  Rene  Oberthur  and  Josef  Jablonowski,  the 
expense  of  getting  these  nests  to  Boston  had  been  very  considerable, 
and  the  moment  when  this  examination  was  begun  was  considered 
to  be  rather  a  critical  one.  Xo  published  record  of  the  rearing  of 
parasites  from  these  winter  nests  was  recalled  by  the  senior  author 
or  by  any  of  his  European  correspondents,  and  the  expensive  experi- 
ment rested  solely  on  the  unpublished  observation  of  Jablonowski, 
and  he  himself  had  simply  seen  parasites  emerge  from  nests  in  the 
spring.  Would  they  prove  useless  $  Had  the  parasitic  insects,  even 
if  useful,  simply  crawled  into  the  nests  for  hibernation  !  ( )r  were  they, 
some  of  them,  true  parasites  of  the  young  larvae  i  Representative  nests 
were  examined  Prom  a  number  of  different  localities,  and  the  relief 

and  joy  were  great  when  parasitic  larva?  were  found  in  considerable 

numbers  in  each  of  t  Ik4  nests  examined,  feeding  within  the  iiesl  pockets 
externally  upon  the  brown-tail  larva1.  This  particular  experiment 
was  a  success,  and  t  he  expenditure  of  money  and  t  rouble  was  justified. 

About  April  25  these  parasites  began  to  issue  from  the  nests.  The 
nests  had  been  gathered  in  all  Prom  33  different  localities,  and  from 
some  of  them  only  a  small  Dumber  of  parasites  was  reared.  In  all, 
about  70, ooo  issued,  of  which  about  s  per  cent  were  hyperparasites. 
In  the  rearing  cages  above  mentioned  it  was  a  comparatively  easy 
matte!-  for  Mr.  Titus  to  separate  the  hyperparasites  Prom  the  true 
parasites  and  to  destroy  the  former.  Of  the  species  issuing  in  that 
spring-  and  they  continued  to  issue  until  about  June  i">    there  were 

two  species  which  appeared  to  be  important,  namely  rt<romahis 
egregius  Fdrst.  and  Habrobrac&n  brevicomis  Wesm.  The  latter  species 
proved  later  to  have  entered  the  nests  for  hibernation  only. 

With  the  cooperation  of  Mr.  Kirkhmd,  several  localities  were  found 
in  which  there  was  slight  danger  of  forest  (ire  and  in  w  hich  no  work 
against  the  moths  would  apparently  be  undertaken  for  at  least  some 
months  to  come,  and  colonies  of  various  sizes — the  three  principal 
ones  including,  respectively,  10,000,  1  o.OOO,  and  25,000  parasites — 
were  liberated  in  the  open.  Outdoor  cages  had  been  built  over  trees, 
and  some  smaller  colonies  of  the  parasites  were  placed  in  these  cages. 
Both  the  outdoor  experiments  and  the  open  experiments  were 
seriously  hampered,  however,  by  the  fact  that  the  season  proved  to 
be  one  of  extraordinary  humidity,  which  caused  the  appearance  of  a 
fungous  disease  which  destroyed  a  large  proportion  of  the  brown-tail 
moth  larva4  in  the  vicinity  of  Boston. 

Coincident  with  the  issuing  of  these  parasites  from  the  nests,  as  the 
season  grew  warm  the  young  larva?  swarmed  from  the  nests  and 
filled  the  glass  tubes  in  the  breeding  cages  and  were  constantly  being 
destroyed  by  the  assistants  in  the  laboratory,  and  when  the  parasites 


62 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


ceased  to  issue  the  remaining  nests  and  larvse  were  burned.  But 
later  observations  showed  this  destruction  to  have  been  a  mistake. 
It  was  not  considered  likely  that  other  parasites  could  be  reared 
from  these  imported  larvse  if  they  were  fed  and  reared  as  far  as  pos- 
sible, but  such  proved  to  be  the  case,  as  will  be  shown  later. 

During  the  winter  of  1905-6  efforts  were  made  to  import  in  winter- 
ing conditions  the  two  large  European  ground-beetles,  Calosoma 
sycophanta  (see  PI.  I,  frontispiece)  and  C.  inquisitor.  No  success  in 
importing  living  specimens  was  gained  until  March,  1906,  but  from 
that  time  on  until  July  small  consignments  of  living  adult  beetles 
were  received,  and  in  all  690  living  specimens  of  Calosoma  sycoplianta 
and  172  of  C.  inquisitor  arrived  at  Boston  alive,  some  of  them  dying 
soon  after  arrival.  Colonies  were  started  in  various  localities  about 
Boston.  Consideration  of  the  history  of  these  two  species  will  be 
given  in  Bulletin  101. 

After  visiting  the  parasite  laboratory  in  March  and  determining 
the  success  of  the  importation  of  the  brown-tail  nests,  the  senior 
author  sailed  from  New  York  on  the  17th  of  the  month  for  Europe, 
returning  to  America  May  17. 

Proceeding  directly  to  Paris,  Mr.  Kene  Oberthiir  was  met  by  appoint- 
ment, and  the  wmole  subject  of  the  summer  work  was  carefully  con- 
sidered. Mr.  Oberthiir  is  a  man  of  affairs,  proprietor  of  a  large 
printing  business,  a  learned  amateur  entomologist,  and  the  possessor 
of  one  of  the  largest  insect  collections  in  the  world.  His  advice  and 
assistance  throughout  the  whole  work  has  been  most  important,  and 
he  assures  the  American  representatives  that  he  has  highly  appre- 
ciated the  opportunity  of  being  of  assistance  and  of  taking  part  in 
such  an  interesting  piece  of  work.  At  his  advice  the  writer  proceeded 
to  the  south  of  France,  after  interviewing  correspondents  and  agents 
in  Paris,  and  visited  Prof.  Valery  Mayet  at  the  agricultural  school 
at  Montpellier,  Dr.  P.  Siepi,  of  the  Zoological  Gardens  in  Marseilles, 
and  Air.  Harold  Powell,  of  Hyeres.  Both  Prof.  Mayet  and  Dr.  Siepi 
stated  that  both  of  the  injurious  species  of  insects  were  rare  in  their 
vicinity,  but  both  promised  to  assist  in  the  importation  of  the  Calosoma 
beetles.  Mr.  Powell  proved  to  be  a  lepidopterist  who  had  been 
employed  professionally  by  Air.  Oberthiir  as  a  collector,  and  he  was 
engaged  to  collect  parasitized  larvse  in  Hydres  and  in  the  Enghadine 
district.  He  sent  in  much  good  material,  and  later,  as  will  be  shown 
in  subsequent  pages,  organized  a  veiy  efficient  service  in  the  summer 
of  1909.  The  visit  to  Prof.  Mayet  at  Montpellier,  moreover,  was  by 
no  means  devoid  of  results,  since  at  a  later  date4  he  was  able  to  send 
a  few  specimens  of  carabid  beetles,  and  in  1908,  as  a  result  of  this 
personal  interview,  he  was  able  to  send  to  America  the  first  living 
specimens  of  the  European  egg  parasite  of  the  imported  elm  leaf- 
beetle,  Tetrastic?iU8  xantJiomelsense  Marchal,  which,  as  a  result  of  this 


NARRATIVE  OF  PROGRESS  OF  WORK. 


63 


Bending,  is  now  possibly  established  in  New  England,  although  it 
was  not  recovered  during  tlwe  summers  of  1900  and  1910. 

While  at  Mar-eillc-  interviewing  Dr.  Siepi,  April  10,  the  news  was 
received  of  the  eruption  of  Vesuvius  and  the  partial  destruction 
by  lava  flow  of  Boscatrecase  and  other  villages  on  the  slope  of 
Vesuvius.  Having  to  interview  Prof.  Silvestri  and  Dr.  Leonardi  at 
Portici,  and  fearing  for  their  safety,  the  visitor  proceeded  at  once  to 
Naples,  arriving  there  the  day  of  the  great  market-house  accident  in 
which  the  roof  fell  in  from  the  weight  of  volcanic  ash  and  a  number 
of  persons  were  killed.  Everything  in  Naples  was  in  a  state  of  con- 
fusion:  the  streets  were  tilled  with  volcanic  ash  almost  knee-deep, 
and  it  was  with  great  difficulty  that  a  conveyance  could  be  secured 
to  drive  to  Portici.  Portici  is  almost  on  a  direct  line  between  Naples 
and  Mount  Vesuvius,  and  the  agricultural  college  was  found  to  be  in 
bad  condition;  the  gardens  were  utterly  destroyed  by  ashes,  and  the 
roof  of  the  old  building  was  deeply  covered.  The  accident  happened 
the  week  before  Kaster,  and  the  majority  of  the  faculty  and  students 
had.  on  account  of  the  catastrophe,  anticipated  their  Kaster  vacations 
and  had  departed  for  their  homes,  Silvestri  and  Leonardi  among  the 
rest.  Letters  were  forwarded  to  them,  however,  giving  detailed 
suggestions  as  to  methods  of  packing  and  shipment  of  parasites. 

As  hi  190."),  Florence,  Milan.  Vienna,  Budapest,  Dresden,  Tharandt, 
and  Zurich  were  visited.  Efforts  were  made  to  learn  of  localities 
where  either  the  gipsy  moth  or  the  brown-tail  moth  might  reasonably 
be  expected  to  be  abundant  dining  the  summer  of  1906,  and  a  number 
of  such  Localities  word  learned  and  the  information  given  lo  agents. 
All  of  the  agents  and  correspondents  were  given  f u II  instructions 
regarding  the  work  for  the  summer  of  1906  and  the  winter  of  1007. 
The  experience4  of  1906  with  regard  to  the  best  methods  of  packing 
and  shipment  and  the  best  kinds  of  boxes  used  was  related  to  all, 
and  these  points  were  full v  discussed,  with  the  result  that  the 
material  received  during  the  summer  of  1906  was  not  only  greater 
in  quantity  but  better  in  condition  than  that  received  during  the 
previo  is  summer. 

In  Vienna  the  visitor  had  the  good  fortune  to  find  Dr.  Gustav 
Mayr,  whom  he  had  missed  in  the  summer  of  1905.  Dr.  Mayr  (since 
deceased)  was  the  European  authority  on  several  of  the  groups  of 
parasites  most  intimately  connected  with  the  work  in  hand,  and  the 
writer  had  a  long  consultation  with  liim  concerning  the  systematic 
position  of  some  of  the  forms  already  imported  and  concerning  the 
practical  possibilities  of  the  whole  series  of  Microhynienoptera. 
Through  him  was  learned  the  probable  importance  of  certain  egg 
parasites  of  the  brown-tail  moth,  which  he  himself  had  reared  in 
Europe  and  had  described.  As  a  result  of  tliis  information  the 
agents  visited  later  were  instructed  to  send  over  egg  masses  of  the 


64 


PARASITES  OF  GIPSY  AND  BROWX-TAIL  MOTHS. 


brown-tail  moth  to  Massachusetts  in  midsummer,  and  later  to  send 
over  egg  masses  of  the  gipsy  moth.  From  the  brown-tail  moth  egg 
masses  parasites  were  reared  by  Mr.  Titus  at  North  Saugus  and 
were  observed  to  oviposit  in  native  eggs.  Mr.  Titus  reared  not 
only  the  species  referred  to  by  Dr.  Mayr,  namely,  Telenomus  pTialse- 
narum  Nees,  which  came  from  eggs  forwarded  by  Miss  Ruhl  and 
collected  in  Croatia,  but  he  also  reared  an  interesting  parasite  of  the 
genus  Trichogramma  from  egg  masses  received  from  Wurtemberg, 
Dalmatia,  and  Rhenish  Prussia. 

At  Budapest  the  visitor  was  especially  glad  to  be  able  to  announce 
to  Prof.  Jablonowski  the  success  of  the  rearings  of  parasites  from  the 
winter  nests  of  the  brown-tail  moth,  so  many  of  which  had  been 
brought  over  from  Europe  the  previous  whiter  on  the  basis  of  Jablo- 
nowski's  unpublished  observations.  At  the  time  of  this  visit  Prof. 
Jablonowski  was  too  busy  completing  his  important  work  upon  the 
migratory  grasshoppers  invading  Hungary  to  be  able  to  promise 
much  assistance  beyond  that  of  corresponding  with  foresters  and 
other  persons  well  located  in  Hungary  in  order  to  obtain  information 
as  to  good  places  to  secure  material. 

Returning  to  America  about  the  end  of  May,  the  laboratory  at 
North  Saugus  was  again  visited,  with  Mr.  Kirkland  and  Mr.  Titus, 
and  the  work  of  preparing  indoor  cages  and  field  cages  was  pushed. 
In  the  course  of  the  summer  a  number  of  outdoor  houses  were  con- 
structed, and  in  these  houses  it  was  hoped  to  study  the  breeding 
habits  of  the  imported  insects. 

During  the  summer  the  number  of  shipments  received  from  Europe 
was  so  large  that  Mr.  Kirkland  made  no  attempt  to  list  them  in  his 
Second  Annual  Report  published  January  1,  1907.  In  June,  in  ad- 
dition to  egg  masses  previously  mentioned,  larvae  and  pupae  of  both  the 
gipsy  moth  and  the  brown-tail  moth  were  received  in  number  from 
man\-  different  European  localities,  and  from  these  a  large  number 
of  parasites  of  several  different  species  were  reared,  the  most  abund- 
ant having  been  tachina  flies.  In  one  lot  received  from  Holland  more 
tachinids  were  reared  than  there  were  gipsy  moth  caterpillars  orig- 
inally. Nearly  40,000  gipsy-moth  larvae  and  pupae  were  received 
and  more  than  35,000  brown-tail  moth  larvae  and  pupae.  The  receipt 
of  predatory  beetles  is  recorded  in  a  previous  paragraph. 

It  will  be  noticed  that  in  the  work  conducted  so  far  the  effort  to 
import  parasites  was  confined  to  the  continent  of  Europe  west  of 
Russia,  whereas  the  well-known  occurrence  at  intervals  in  large 
numbers  of  the  gipsy  moth  in  parts  of  Russia,  and  especially  in 
southern  Russia  (a  very  good  account  of  which  will  be  found  in  the 
Third  Report  on  the  Gipsy  Moth,  by  Forbush  and  Fernald),  seemed 
to  render  it  desirable  that  search  should  be  made  in  those  regions 
for  parasites.    The  fact,  however,  that  during^  these  two  years 


NARRATIVE  OF  PROGRESS  OF  WORK. 


65 


the  writer  had  heen  unable  to  secure  answers  to  letters  addressed 
to  correspondents  in  Russia  and  the  reported  unsettled  condition 
of  affairs  in  that  country  deterred  him  during  the  1905  and  1906 
trips  from  visiting  the  Russian  southern  Provinces.  In  the  late 
summer  of  1906,  however,  advices  were  received  from  Prof.  J.  Por- 
chinsky,  of  the  ministry  of  agriculture  at  St.  Petersburg,  with  the 
information  that  in  the  southern  part  of  Russia  both  the  gipsy  moth 
and  the  brown-tail  moth  were  at  that  time  occurring  in  sufficiently 
great  numbers  to  enable  the  collection  of  parasite-  and  commending 
the  writer  to  certain  officials,  trained  entomologists,  in  Simferopol 
(Crimea),  Kishenef  (Bessarabia),  and  Kief.  Prof.  Porchinsky  wrote 
that  he  had  apprised  these  officials  of  the  intended  visit,  and  plans 
were  therefore  made  to  include  southern  Russia  in  the  itinerary  for 
the  spring  of  1907. 

During  the  autumn  of  1906  egg  masses  of  the  gipsy  moth  con- 
tinued to  be  received  from  parts  of  Europe,  and  during  the  winter 
hibernating  nests  of  the  brown-tail  moth  were  sen!  in.  More  than 
111,000  nests  were  received  from -different  portions  of  the  European 
range  of  the  species.  These  were  placed  in  the  especially  constructed 
cages,  and  from  many  <>f  them  large  numbers  of  parasites  were 
reared,  issuing  mainly  (hiring  the  month  of  May,  1907.  As  it  hap- 
pened, the  month  of  May  in  New  England,  as  well  as  in  other  parts 
of  the  United  States,  was  phenomenally  cold  and  wet.  As  a  result 
of  this  unlooked-for  condition  very  many  of  the  parasites  refused 
to  leave  the  nests  until  they  were  so  weakened  as  to  be  unable  to 
survive  the  close  confinement  and  careful  scrutiny  to  which  they 
were  necessarily  subjected  in  order  to  eliminate  the  danger  of  intro- 
ducing secondary  parasites.  As  a  result,  a  smaller  number  of  Ptero- 
mahu  egregivs  was  colonized  in  tjie  summer  of  1906,  but  40,000  speci- 
mens were  put  out  in  several  localities,  the  principal  colonies  consist- 
ing, respectively,  of  13,000,  11,000,  and  7,000  individuals.  At  this 
time,  as  well  as  in  the  summer  of  1906,  although  this  fact  has  not  as 
yet  been  stated,  a  number  of  important  parasites  of  the  genus  Mono- 
dontomerus  issued  from  the  winter  nests  and  were  allowed  to  escape. 
As  will  be  shown  subsequently,  this  parasite  has  proved  to  be  more 
important  than  the  Pteromalus  and  has  made  a  phenomenal  spread. 

In  this  important  work  with  the  introduced  hibernation  nests 
of  the  brown-tail  moth  it  was  early  found  most  difficult  to  preserve 
the  health  of  the  laboratory  assistants.  The  irritating  and  poisonous 
hairs  of  the  brown-tail  moth  larvse,  of  which  the  nests  are  full,  soon 
penetrated  the  skin  of  the  assistants  handling  them,  entered  their 
eyes  and  throats,  and  the  atmosphere  of  the  laboratory  became 
almost  filled  with  them.  It  was  necessary  that  the  rooms  should 
be  kept  thoroughly  closed;  double  windows  and  screens  were  used, 

95GT70— Bull.  91— U  5 


66  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

and  the  doors  of  the  rooms  were  doubled,  in  order  that  a  possible 
secondary  parasite,  if  accidentally  liberated,  should  have  no  chance 
of  escape.  This  made  the  rooms  very  warm  and  increased  the 
irritating  effect  of  the  larval  hairs.  Some  of  the  assistants  employed 
could  not  stand  the  work  and  resigned.  One  of  the  best  and  most 
experienced  helpers  was  induced  to  continue  the  second  year  only 
upon  the  promise  that  he  would  be  relieved  from  this  especial  class  of 
work.  Spectacles,  gloves,  masks,  and  even  headpieces  were  invented 
to  avoid  this  difficulty,  but  these,  while  greatly  increasing  the  suffer- 
ing from  the  heat,  were  not  entirely  effective.  The  most  serious 
result  of  this  trouble  was  the  breaking  down  in  health  of  Mr.  E.  S.  G. 
Titus  of  the  bureau,  in  charge  of  the  laboratory  at  Saugus,  who  was 
obliged  to  resign  in  May,  1907,  on  his  physician's  advice,  in  order 
to  save  his  life.  The  difficulty  in  Mr.  Titus's  case  was  the  intense 
irritation  to  his  lungs  from,  the  entrance  of  the  barbed  hairs.  Mr. 
Titus  was  soon  after  appointed  entomologist  of  the  Utah  Agricul- 
tural Experiment  Station,  and  the  change  of  work  and  climate 
fortunately  brought  about  a  speedy  recovery.  His  necessitated 
departure  in  the  midst  of  important  work,  however,  threw  us  into 
what  appeared  to  be  a  serious  dilemma,  but  fortunately  it  so  hap- 
pened that  the  services  of  the  junior  author,  then  occupying  another 
position  in  the  Bureau  of  Entomology  in  Washington,  could  be 
spared  from  the  other  work  upon  which  he  had  been  engaged,  and, 
since  he  had  made  especial  studies  of  the  parasitic  Hymenoptera 
and  had  done  a  large  amount  of  rearing  of  parasites  in  the  course  of  his 
other  work,  he  was  sent  on  from  Washington  to  replace  Mr.  Titus 
in  the  parasite  laboratory  and  has  since  had  charge  of  the  laboratory. 

One  of  the  early  points  to  which  the  junior  author  devoted  his 
attention  was  the  invention  of  new  methods  of  handling  the  brown- 
tail  nests  in  order  to  avoid  the  serious  effect  upon  the  work  of  the 
breaking  out  of  the  rash  on  himself  and  his  assistants.  He  soon 
devised  an  apparatus  like  the  ordinary  show  cases  that  are  seen  in 
shops,  the  glass  on  one  side  being  replaced  by  cloth  with  armholes, 
through  which  the  gloved  hands  of  the  worker  could  be  thrust  and 
the  brown-tail  nests  handled  in  full  sight  through  the  top  glass. 
Most  of  the  work  with  these  nests,  it  has  been  found,  can  be  done  in 
these  cases  with  a  minimum  escape  of  the  barbed  hairs.  There  still 
continued,  however,  considerable  trouble  from  the  rash,  since  much 
rearing  of  brown-tail  larvae  must  be  carried  on  under  conditions  in 
which  such  cases  can  not  be  used,  and  this  difficulty  still  exists. 
Miss  rliihl,  of  Zurich,  in  handling  and  repacking  t  he  large  number  of 
nests  sent  to  her  by  her  European  correspondents  and  forwarded  by 
her  to  Boston,  has  been  a  great  sufferer  from  the  rash.  She  has  made 
for  herself  a  complete  costume  of  iii!  especially  finely  woven  cloth, 
and  has  made  a  large  light  helmet  covered  with  cloth  and  provided 


NARRATIVE  OF  PROGRESS  OF  WORK. 


67 


with  a  capo,  the  space  opposite  the  eyes  being  fitted  with  a  sheet  of 
very  transparent  celluloid.  Of  course  tins  costume  would  be  very 
uncomfortable  in  the  summer  time  on  account  of  the  heat,  but  since 
she  handles  her  nests  for  the  most  part  in  the  autumn  and  winter, 
she  has  been  able  to  reduce  the  discomfort  of  the  brown-tail  rash  to 
a  minimum. 

Sailing  again  for  Europe  on  April  20,  1907,  the  senior  author  landed 
at  Cherbourg  and  proceeded  directly  to  Paris,  and  from  Paris  to 
Budapest  by  the  Oriental  Kxpress.  At  Budapest,  by  prearrange- 
ment,  lie  met  Mr.  Alexander  Pichler,  whom  he  had  engaged  as  a 
guide  and  courier  for  the  Russian  trip.  After  a  conference  at  Buda- 
pest with  Dr.  Ilorvath  and  Prof.  Mocsary,  of  the  Natural  History 
Museum,  and  Prof.  Jablonowski,  of  the  agricultural  station,  he  pro- 
ceeded to  Kief,  via  Lemburg.  Prof.  Porchinsky,  of  the  ministry  of 
agriculture,  had  arranged  with  Prof.  Waldemar  Pospielow,  of  the 
rniversity  <>f  Kief,  to  consult  with  the  Chief  of  the  Bureau  of  Ento- 
mology about  future  arrangements,  and  a  conference  with  Prof. 
Pospielow  was  held,  in  the  course  of  which  it  was  agreed  that  one  of 
Pospielow  s  assistants,  engaged  especially  for  the  purpose,  at  34 
rubles  per  month,  should  occupy  himself  throughout  the  summer, 
under  Pospielow's  directions,  in  collecting  larvse  of  the  gipsy  moth 
and  brown-tail  moth,  forwarding  material  to  Boston,  rearing  and 
studying  the  parasites,  and  conducting  observations  in  an  orchard 
in  the  suburbs  of  Kief,  rented  by  the  writer  for  the  State  of  Massa- 
chusetts for  the  summer  at  the  rate  of  20  rubles  per  month.  'Phis 
procedure  was  novel  in  the  work,  but  was  later  tried  in  another 
locality,  as  will  be  shown  in  subsequent  pages. 

From  Kief,  Pichler  and  the  visitor  proceeded  to  Odessa  and  from 
Odessa  to  Kishenef,  at  w  hich  point  he  had  been  recommended  to  Dr. 
Isaak  Krassilstschik  by  Prof.  Porchinsky.  Through  some  mis- 
understanding  as  to  dates,  owing    to  the  diH'erence  between  the 

Russian  calendar  and  the  one  in  use  in  other  parts  of  the  world,  Prof. 
Krassilstschik  had  mistaken  the  date  of  arrival  announced  in  the 
letter  lent  in  advance,  and  was  absent  from  Kishenef  on  a  brief  visit 
to  Germany.  Full  written  instructions,  however,  wore  left  for  him 
at  Kishenef,  and  the  visitor  returned  to  Odessa  and  thence  by  boat 
to  Sebastopol,  and  by  train  to  Simferopol.  At  Simferopol  he  was 
expected  by  Prof.  Sigismond  Mokshetsky,  the  director  of  the  Museum 
of  Natural  History  at  that  place  and  an  enthusiastic  economic  ento- 
mologist, through  whose  efforts  American  methods  in  the  warfare 
against  insects  had  been  introduced  into  southern  Russia.  Prof. 
Mokshetsky  had  done  some  rearing  of  the  Russian  parasites  of  both 
the  gipsy  moth  and  the  brown-tail  moth,  and  was  able  to  furnish 
much  valuable  information.  His  hospitality  and  cordiality  were  of 
the  most  encouraging  nature,  and  after  consultation  as  to  the  best 


68 


PARASITES  OF  GIPSY  AND  BROWX-TAIL  MOTHS. 


methods,  he  promised  his  hearty  support  to  the  work,  refusing,  how- 
ever, to  accept  any  compensation  from  the  State  of  Massachusetts  or 
from  the  United  States  Government. 

The  visitor  then  proceeded  by  boat  from  Sebastopol  to  Con- 
stantinople, but  was  unable  to  learn  of  any  person  in  Turkey  having 
any  information  on  the  subject  of  insect  pests,  nor  was  he  able  in  the 
country  about  Constantinople  to  find  any  indication  of  the  occurrence 
of  either  gipsy  moth  or  brown-tail  moth. 

Leaving  Constantinople,  the  expedition  proceeded  to  Vienna,  drop- 
ping Mr.  Pichler  at  Budapest.  At  Vienna  the  Seventh  International 
Congress  of  Agriculture  was  held,  beginning  May  22,  1907.  The 
visitor  met  there  a  number  of  delegates  from  the  different  countries 
in  Europe,  with  whom  he  discussed  the  question  of  parasite  importa- 
tion, receiving  warm  assurances  of  support,  especially  from  Prof.  Dr. 
Max  Hollrung,  of  the  Agricultural  Department  of  the  University  of 
Halle,  Prof.  Dr.  Karl  Eckstein,  of  the  Forest  Academy  at  Ebers- 
walde,  and  Prof.  Dr.  J.  Kitzema  Bos,  director  of  the  Phytopatho- 
logical  Station  at  TVageningen,  Holland.  "While  in  Vienna  arrange- 
ments were  made  with  Mr.  Fritz  WTagner  for  continuance  of  the 
work,  and  a  further  consultation  on  the  subject  of  parasites  was  held 
with  Dr.  Gustav  Mayr. 

After  Vienna,  Mr.  Schopfer  was  visited  in  Dresden,  Dr.  Hollrung 
at  Halle,  Dr.  R.  Heymons  in  Berlin,  Dr.  Eckstein  in  Eberswalde, 
Miss  Riihl  at  Zurich,  and  Prof.  G.  Severin  at  Brussels.  Prof.  Severin 
is  connected  with  the  Royal  Natural  History  Museum  at  Brussels, 
is  an  admirably  well-posted  entomologist,  and  is  connected  with  the 
Forest  Conservation  Commission  of  Belgium.  He  was  able  to  give 
good  advice  in  the  parasite  work  and  promised  assistance. 

Returning  to  France,  an  important  conference  was  held  with  Mr. 
Rene  Oberthiir,  and  it  was  arranged  to  establish  during  the  summer 
of  1908  a  field  station  at  Rennes,  to  be  placed  in  charge  of  a  special 
expert,  Mr.  A.  Vuillet,  chosen  by  Prof.  Houlbert,  of  the  University 
of  Rennes.  Through  Mr.  Oberthur's  courtesy  it  was  arranged  to 
establish  field  rearing  cages  at  a  convenient  point  near  the  University 
of  Rennes  and  to  carry  on  the  work  in  much  the  same  way  as  it  had 
been  arranged  for  the  present  summer  at  Kief.  The  University  of 
Rennes  having  a  certain  connection  with  the  University  of  Paris,  it 
was  considered  desirable  that  the  cooperation  of  the  scientific  faculty 
of  the  University  of  Paris  be  gained  by  direct  application.  This  was 
readily  arranged,  through  the  cordial  and  sympathetic  cooperation 
of  Prof.  Alfred  Giard,  of  the  faculty  of  science  of  the  University  of 
Paris  (since  deceased). 

Tn  dealing  with  the  European  parasites  reared  at  North  Saugus, 
considerable  difficulty  was  experienced  in  ascertaining  their  names. 
It  was  very  desirable,  of  course,  to  have  a  definite  name  by  which  to 


NARRATIVE  OF  PROGRESS  OF  WORK. 


69 


designate  each  species,  and  by  which  to  correlate  it  with  published 
accounts  of  observations  already  made.  With  the  assistance  of  Dr. 
().  Schmiedeknecht.  of  Cassel,  Germany,  a  number  of  these  forms  had 
been  named,  but  with  others  it  seemed  practically  impossible  to  bring 
this  about  by  correspondence.  As  a  result,  on  the  trip  in  question 
the  writer  made  an  effort,  by  studying  the  collections  in  some  of  the 
principal  European  museums,  to  determine  a  few  of  the  unnamed 
forms  reared  in  America  from  European  material.  The  difficulty  of 
this  search  was  surprising.  The  Pteromalus,  for  example,  which  had 
been  reared  in  Boston  by  scores  of  thousands  and  which,  there- 
fore, must  be  a  very  common  European  insect,  was  found  to  be 
absolutely  unrepresented  in  the  large  natural  history  museums  of 
Vienna,  Dresden,  Berlin,  Brussels,  and  London;  nor  did  it  occur  in 
the  type  collections  of  Ratzeburg  carefully  preserved  by  Dr.  Eck- 
stein at  the  Forest  Academy  at  Eberswalde,  where,  on  account  of 
Ratzeburg's  important  work  on  the  parasites  of  European  forest 
insects,  <>ne  would  naturally  expect  to  find  it.  At  last,  in  a  small 
special  collection  in  the  Museum  of  Natural  History  in  the  Jardin 
des  Plantes  at  Pari-.  Mr.  II.  du  Buyason  of  the  museum  found  in  the 
laboratory  a  box  containing  parasites  reared  many  years  ago  by  the 
French  entomol< »<_ri-i .  Sichel,  which  had  been  named  for  him  by  the 
eminent  authority  on  parasitic  Hymenoptera,  Arnold  Forster,  of 
Germany.  In  this  box  were  specimens  of  the  Pteromalus  labeled 
"Ft.  ((/n  </'<)is"  in  the  handwriting  of  Forster  himself. 

Especial  efforts  were  made  on  the  trip  to  arrange  for  the  importa- 
tion of  large  numbers  of  the  egg  parasites  of  both  species  and  to 
introduce  in  living  condition  the  important  parages  of  the  genus 
Apanteles.  which,  according  to  the  visitor's  field  observations,  are 
anmng  the  most  important  of  the  European  enemies  of  the  gipsy 
moth.  Previous  importations  of  these  parasites  had  failed,  owing 
t<»  the  fact  that  they  emerged  and  died  on  the  journey.  On  this 
trip,  however,  specific  directions  were  given  to  agents  to  send  in 
young  larva*  of  the  second  stage,  and  by  this  means  living  specimens 
in  considerable  numbers  were  later  reared  in  the  laboratory  at  North 
Saugus.  These  on  issuing  laid  their  eggs  in  the  gipsy-moth  larvse 
of  the  first  stage,  and  from  these  caterpillars  were  secured  the 
cocoons  of  adults  of  a  second  generation  which  was  reared  through 
all  of  its  stages  on  American  soil. 

From  Kief  there  were  received  two  species  hitherto  unknown  as 
parasites  of  the  gipsy  moth,  and  one  of  these,  being  a  rapid  breeder, 
promised  to  be  of  much  assistance.  This  species,  belonging  to  the 
genus  Meteorus,  seemed  to  produce  cocoons  in  about  10  days  after 
egg  laying,  and  will  be  considered  later  in  this  bulletin. 

We  have  previously  referred  to  the  destruction  in  1906  of  the 
great  bulk  of  brown-tail  caterpillars  imported  from  Europe  after  the 


70 


PARASITES  OF  GTPSY  AND  BROWN-TAIL  MOTHS. 


early  appearance  of  adult  parasites.  Mr.  Titus,  in  1906,  tried  the 
experiment  of  rearing  a  very  few  of  these  imported  larvae,  and  found 
that  in  their  later  growth  they  gave  out  a  second  lot  of  parasites 
entirely  different  from  those  reared  in  May  from  the  very  young 
hibernating  larvae,  indicating  a  delayed  development  of  eggs  which 
must  have  been  laid  by  adult  parasites  the  previous  autumn.  Among 
these  were  at  least  two  species,  one  belonging  to  the  genus  Apanteles 
and  the  other  a  Meteorus.  Before  his  resignation  in  1907  he  started 
an  extensive  series  of  rearing  experiments  with  the  end  in  view  of 
securing  these  parasites  in  large  numbers.  Partly  on  account  of  his 
enforced  absence  from  the  laboratory  during  a  critical  period,  and 
partly  through  the  unsuitable  character  of  the  rearing  cages  which 
were  employed,  the  project  did  not  meet  with  entire  success.  Only 
about  1,000  of  the  parasites  were  reared,  of  which  all  but  a  small 
percentage  were  the  Apanteles. 

The  importations  of  the  summer  following  the  trip  above  described 
were  very  large,  and  reasonably  successful,  and  during  June  alone 
872  boxes  were  received,  many  others  following  during  July  and  into 
August,  shipments  of  brown-tail  eggs  and  gipsy-moth  eggs  following, 
and  of  brown-tail  winter  nests  in  the  late  autumn  and  during  the 
winter.  As  in  1906,  tachinids  made  up  the  great  bulk  of  the  para- 
sites secured  through  the  importation  of  pupae  and  active  caterpillars. 
Notwithstanding  the  improvement  in  methods  of  shipment  over 
previous  years,  Apanteles  invariably  hatched  en  route,  and  only  dead 
adults  or  secondary  parasites  were  received. 

Before  the  close  of  the  summer  it  had  become  obvious  that  better 
quarters  for  the  Massachusetts  laboratory  were  necessary.  The 
heating  and  lighting  arrangements  at  North  Saugus  were  insuffi- 
cient ;  the  building  was  not  sufficiently  commodious,  and  the  location 
was  not  convenient.  Therefore,  after  considerable  search,  Mr. 
Kirkland  found  and  leased  for  a  term  of  years  a  commodious  house 
at  Melrose  Highlands  (No.  17  East  Highland  Avenue)  (see  PL  II, 
fig.  2,  p.  56.)  The  building  was  remodeled  so  far  as  necessary  to  fit 
it  for  the  work.  The  grounds  back  of  the  house  were  sufficiently 
ample  to  enable  the  building  of  several  outdoor  laboratories,  properly 
screened  and  ventilated,  which  were  planned  and  erected  under  the 
direction  of  the  junior  author.  The  building  is  well  warmed,  lighted 
with  electricity,  and,  being  close  to  fire  protection,  possesses  many 
advantages  over  the  old  laboratory.  Moreover,  it  is  much  nearer 
the  central  office  in  Boston,  enabling  an  important  saving  of  time  in 
sending  to  the  laboratory  shipments  of  parasites  received  from  abroad. 
The  rental  and  the  expense  of  construction  were  all  borne  by  the 
State  of  Massachusetts.  The  new  quarters  are  also  within  a  stone's 
throw  of  a  large  area  of  waste  land  covered  with  scrub  oak. 


NARRATIVE  OF  PROGRESS  OF  WORK. 


71 


In  planning  the  work  for  the  season  of  1908,  several  new  features 
wm  introduced.  The  parasites  constantly  sent  over  by  agents 
belong  to  three  main  groups,  namely,  those  of  the  order  Hymenop- 
tera,  including  the  ichneumon  flies,  the  chalcis  flies,  and  others; 
those  of  the  Dipt  era.  including  the  tachina  flies,  and  those  of  the 
oiilcr  Coleoptera,  including  the  predaceous  ground  beetles.  The 
amount  of  material  received  had  been  so  great,  and  the  character  of 
the  different  life  histories  of  the  insects  involved  had  been  so  diverse, 
that  no  one  expert  was  able  to  do  the  fullest  justice  to  the  situation. 
Therefore,  while  the  junior  author  was  left  in  general  charge  of  the 
whole  mass  of  importations  and  retained  his  expert  supervision  of 
the  work  on  the  biology  of  the  parasitic  Ilvnienoptera,  Mr.  C.  H.  T. 
Townsend,  of  the  Bureau  of  Entomology,  was  assigned  to  the  work 
on  the  biology  of  the  dipterous  parasites,  and  Mr.  A.  F.  Burgess,  also 
of  the  Bureau  of  Entomology,  was  assigned  to  the  expert  charge  of 
I  lie  ground  beetles. 

Owing  to  the  fact  that  the  condition  of  European  sendingS  by  mail 
and  express  during  the  summer  of  1907  had  been  by  no  means  uni- 
formly good — those  from  eastern  Europe,  subjected  to  long  railway 
journeys  in  addition  to  the  sea  voyage,  frequently  arriving  in  bad 
condition  the  second  innovation  was  made  by  establishing  at 
Rennes,  France,  a  general  laboratory  depot  in  addition  to  the  Reld 
cages  and  rearing  station  mentioned  in  a  previous  paragraph.  The 
expert  assistant  designated  by  Prof.  Houlbert,  of  the  University  of 
Etennes,  was  Mr.  A.  \  uillet,  who  was  placed  in  specific  charge  of  the 
general  laboratory  depot  under  the  general  supervision  of  Mr.  Rene 
Oberthiir.  Mr.  Yuillet  placed  himself  in  relations  with  the  steamship 
company  agents  at  Cherbourg  and  Havre  and  was  kepi  informed  as 
to  the  dates  of  the  sailings  of  steamers.  Nearly  all  of  the  European 
sendings  were  shipped  to  Kennes,  examined,  repacked,  and  carried 
personally  by  Mr.  Yuillet  to  Cherbourg  or  Havre  on  the  known  days 
of  sailing  of  certain  steamers  and  then  placed  in  the  hands  of  chief 
stewards  of  the  vessels  and  carried  in  the  cold  rooms  to  New  York, 
wherce  they  were  sent  to  Boston.  Early  in  the  course  of  the  work 
the  honorable  the  Secretary  of  the  Treasury,  upon  request  of  the 
honorable  the  Secretary  of  Agriculture,  had  issued  orders  to  the  col- 
lector of  the  port  of  New  York  to  admit  all  such  packages  without 
examination  and  to  hasten  their  departure  for  Boston  through  the 
United  States  dispatch  agent.  The  steamship  oflicials  showed  them- 
selves uniformly  courteous,  and  as  a  result  of  this  new  arrangement 
the  average  condition  of  the  material  received  proved  to  be  much 
better. 

With  the  installation  of  the  new  laboratory  at  Melrose  Highlands, 
and  with  the  added  space  afforded  by  the  new  structures  in  the  gar- 


72 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


den,  the  junior  author  was  able  to  carry  out  some  new  ideas  with 
admirable  results.  The  first  of  these  was  the  carrying  on  of  active 
winter  work  with  parasites,  especially  those  secured  from  the  imported 
nests  of  the  brown-tail  moth,  which  began  to  come  in  from  Europe 
in  December.  It  was  found  quite  possible  to  rear  these  parasites 
in  artificially  heated  rooms,  feeding  them  upon  hibernating  native 
brown-tail  larvae  brought  in  in  their  nests  from  out  of  doors,  feeding 
the  latter  upon  lettuce  and  other  hothouse  foliage,  and  in  the  early 
spring  securing  more  normal  food  for  them  by  sending  it  up  in  boxes 
by  mail  from  Washington  and  points  south.  In  this  way  the  rear- 
ing of  the  parasites  of  the  genus  Pteromalus  was  carried  forward 
uninterruptedly  throughout  the  winter,  and,  as  during  the  rearing  of 
successive  generations  they  multiplied  exceedingly,  it  was  possible 
later  in  the  year  to  liberate  a  vastly  greater  number  of  individuals 
than  had  the  imported  species  been  allowed  to  hibernate  normally  in 
the  nests.  In  the  course  of  this  work  the  junior  author  invented  a 
rearing  tray  which  was  of  the  utmost  advantage  and  which  has  since 
greatly  facilitated  parasite  rearing  work.  This  tray  will  be  described 
later. 

With  the  importation  of  brown-tail  moth  eggs  it  often  happened 
that  they  hatched  too  soon  to  be  of  use  in  America;  or  too  late, 
arriving  after  the  American  eggs  had  all  hatched.  It  was  ascertained 
by  the  junior  author  during  the  summer  and  autumn  that  native  eggs 
can  be  kept  in  cold  storage  until  the  arrival  of  the  European  egg 
parasites,  which  were  found  to  la}r  their  eggs  and  breed  in  these  cold- 
storage  eggs  as  freely  as  in  those  which  they  attack  in  the  state  of 
nature.  It  was  found  that  this  process  can  be  carried  on  for  a  long 
time,  and  that  successive  generations  of  these  egg  parasites  may  be 
reared  from  eggs  retarded  in  their  development  by  cold  storage.  It 
was  thus  shown  that  it  is  easy  to  rear  and  liberate  an  almost 
infinitely  greater  number  of  these  egg  parasites,  and  under  favorable 
conditions,  than  would  have  been  possible  from  a  simple  importation 
of  European  parasitized  eggs  which  would  have  to  arrive  in  America 
at  a  specific  time. 

In  the  same  way  great  advance  was  made  in  the  rearing  of  the 
tachinid  parasites  in  Mr.  Townsend's  charge.  This  expert  devised 
methods  and  made  observations  that  greatly  added  to  our  knowledge 
of  the  biology  of  these  insects  and  resulted  in  the  accumulation  of  a 
store  of  information  of  the  greatest  practical  value,  not  only  in  the 
prosecution  of  the  present  undertaking  but  in  any  problem  of  parasite 
introduction  or  control  that  may  arise  later.  Extraordinary  and 
almost  revolutionary  discoveries  were  made  in  the  life  histories  of 
certain  of  these  flies,  and  without  this  knowledge  the  greatest  success 
in  1  land  ling  them  practically  could  not  have  been  reached.  Certain 
of  these  facts  regarding  the  most  important  of  these  parasites  are 


NARRATIVE  OF  PROGRESS  OF  WOKK. 


73 


related  in  a  later  part  of  this  bulletin,  and  many  of  them  have  been 
described  in  some  detail  in  Technical  Series  No.  12,  Part  VI,  Bureau 
of  Entomology,  United  States  Department  of  Agriculture  (190S), 
by  Mr.  Townsend. 

Similarly  Mr.  Burgess,  in  charge  of  the  Coleoptera,  succeeded  in 
u  very  perfect  way  in  rearing  and  liberating  the  important  European 
predatory  beetle,  Calosoma  sycophemta,  as  well  as  some  other  insects 
of  the  family  Carabid®. 

While  these  extensive  importations  from  Europe  were  going  on, 
Japan  had  by  no  means  been  lost  sight  of.  While  it  seemed  probable 
that  the  European  parasites  in  themselves  would  succeed  in  reestab- 
lishing the  balance  of  nature  in  New  England,  and  in  spite  of  the 
somewhat  dangerous  nature  of  Japanese  importations  on  the  ground 
that  the  Japanese  gipsy  moth  is  probably  a  different  species  and 
might  prove  in  New  England  even  more  voracious  and  destructive 
than  the  European  moth,  there  as  at  DO  time  any  intention  to  neglect 
Japan  in  the  search  for  effective  parasites.  Continuous  correspond- 
ence had  been  carried  on  with  Japanese  entomologists,  and  some 
shipments  had  been  made  by  correspondents  which  resulted  unsuc- 
cessfully. For  sonic  time  the  Apanteles  previously  mentioned  was 
the  only  gipsy-moth  parasite  known  to  occur  in  Japan.  Later 
information  was  received  from  Prof.  U.  Nawa,  of  Gifii,  Japan,  to  the 
effect  that  there  exists  in  Japan  an  important  egg  parasite  of  the 
gipsy  moth.  Dining  tin4  previous  annual  trips  of  the  Chief  of  the 
Bureau  of  Entomology  to  Europe  the  European  service  of  collectors, 

agents,  and  advisers  had  been  well  organized  and  instructed,  and  the 
work  during  1908  was  reasonably  sure  to  be  well  continued  without 
further  personal  consultation:  it  was  therefore  decided  to  interrupt 
the  European  trip  for  1!K)S  and  to  send  a  skilled  agent  to  Japan.  In 
considering  the  appointment  of  such  an  agent,  Prof.  Trevor  Kincaid, 
of  the  University  of  Washington  at  Seattle,  was  at  once  suggested 
to  the  mind  of  the  writer,  primarily  on  account  of  his  extraordinary 
skill  as  a  collector,  as  indicated  in  the  remarkable  results  of  his  work 
on  the  Harriman  expedition  to  Alaska  in  lMMt,  and  also  on  account 
of  his  comparative  proximity  to  Japan  and  the  fact  that  he  was  per- 
sonally acquainted  with  many  persons  in  Japan.  Jle  was  therefore 
recommended  to  the  State  officials  of  Massachusetts  for  appointment, 
and  was  commissioned  by  the  State  to  undertake  the  expedition. 
At  the  same  time  he  was  formally  appointed  a  collaborator  of  the 
Bureau  of  Entomology  of  the  United  States  Department  of  Agricul- 
ture, and  the  Japanese  Government  was  formally  notified  by  the 
honorable  the  Secretary  of  Agriculture,  through  the  Department  of 
State,  of  the  intended  visit,  the  writer  having  also  notified  by  per- 
sonal correspondence  some  of  the  well-known  Japanese  entomologists. 
Prof.  Kincaid  sailed  from  Seattle  on  March  2,  and  the  results  of  his 


74 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


expedition  far  more  than  justified  the  expense  involved.  A  very 
large  amount  of  parasite  material  was  received  from  him  in  good 
condition  at  Boston,  and  very  many  parasites  from  Japan  were 
colonized  in  the  woodlands  in  New  England.  Prof.  Kincaid  was 
received  with  the  most  extreme  courtesy  and  cordiality  by  the 
Japanese  Government  and  by  .official  and  private  entomologists 
everywhere.  His  work  was  facilitated  in  every  possible  way;  assist- 
ants were  placed  at  his  disposal  and  in  this  way  a  large  number  of 
individuals  occupied  themselves  in  the  collection  of  parasitized 
material.  After  consultation  with  the  Japanese  entomologists, 
whose  great  cleverness  in  manipulation  and  ingenuity  in  devising 
methods  are  well  known,  Prof.  Kincaid  was  able  to  pack  his  shipments 
in  such  a  way  as  to  bring  about  a  minimum  of  mortality  on  the  jour- 
ney. The  steamship  companies  showed  him  every  courtesy,  and 
much  of  his  material  arrived  at  Melrose  Highlands  in  better  condition 
than  corresponding  sendings  received  from  Europe.  A  single  indi- 
cation of  the  value  of  Prof.  Kincaid's  work  may  be  mentioned :  From 
one  shipment  of  cocoons  between  40,000  and  50,000  adults  of  the 
Japanese  Apanteles  were  reared  and  were  liberated  directly  in  the 
open  in  Massachusetts,  and  this,  is  the  species  which,  although 
repeatedly  sent  by  correspondents,  had  never  arrived  in  New  England 
in  such  condition  that  a  single  living  adult  could  be  reared. 

The  European  importations  in  the  meantime  continued  to  arrive 
in  numbers,  and  at  the  close  of  the  summer  it  was  found  that  the 
actual  number  of  beneficial  insects  liberated  had  been  far  in  excess 
of  that  for  1906  or  1907,  and  that  the  list  included  several  species 
of  apparently  great  importance  and  promise  that  had  never  before 
been  received  at  the  laboratory  in  living  condition. 

The  successful  European  importations  all  came  from  western 
Europe,  and  unfortunately  the  few  shipments  sent  from  Russia 
arrived  in  very  bad  condition.  This  is  considered  to  have  been  most 
unfortunate,  since  several  of  the  Russian  parasites  were  very  promis- 
ing, and  the  subject  of  improving  the  Russian  service  was  taken  into 
consideration. 

With  the  great  success  of  the  summer's  Japanese  work,  and  the 
quest  ion  of  the  great  desirability  of  similar  work  in  Russia  in  his  mind, 
the  senior  author,  visiting  the  Pacific  coast  in  the  autumn  of  that 
year  (1908)  on  a  tour  of  inspection  of  the  field  laboratories  of  the 
Bureau  of  Entomology,  called  on  Prof.  Kincaid  at  Seattle  and  dis- 
cussed with  him  at  length  the  plans  for  1909.  Although  Kincaid 
expressed  himself  as  charmed  with  Japan  and  anxious  to  repeat  bis 
visit  to  thai  most  interesting  country,  liis  innate  honesty  compelled 
him  to  state  that  he  considered  the  expense  of  the  trip  unnecessary: 
that  lie  had  found  the  Japanese  entomologists,  officials,  and  others 
so  intelligent  and  so  thoroughly  competent,  and  at  the  same  time 


NARRATIVE  OF  PROGRESS  OF  WORK. 


75 


so  heartily  interested  in  the  experiment,  that  he  considered  them 
noi  only  perfectly  able,  but  perfectly  willing  to  carry  on  the  work  by 
themselves.  After  this  authoritative  expression  of  opinion  from  one 
who  knew  the  ground  so  well,  the  visitor  asked  Mr.  Kineaid  whether 
he  would  care  to  spend  the  early  summer  months  of  1909  in  Russia, 
and,  upon  his  aflirmat  ire  reply,  later  recommended  his  reappointment 
to  the  Massachusetts  State  authorities  for  that  purpose. 

During  the  autumn  and  winter  shipments  of  eggs  of  the  gipsy 
moth  were  received  from  Japan,  principally  from  Prof.  Kuwana. 
From  these  eggs  were  reared  numerous  specimens  of  Anastatux  bifas- 
datus  Fonsc,  a  previously  known  European  parasite  of  these  eggs, 
and  of  another  parasite  belonging  to  a  genus  and  species  new  to 
science  (since  named  by  the  senior  author  Schedius  L  ftvatix)  which 
has  turned  out  to  be  an  important  primary  parasite  and  which  is 
considered  in  later  pages.  During  the  winter,  also,  Prof.  Jablonow  Bki, 
of  Budapest ,  sent  over  several  thousand  egg  masses  of  the  gipsy  moth 
collected  in  various  localities  in  Hungary.  After  they  arrived  in 
Massachusetts  there  were  reared  from  them  and  Liberated  under  the 
most  favorable  conditions  more  than  75,000  adult  individuals  of 
Anastdtus  bifasciatus.  This  was  a  surprising  thing  to  the  laboratory 
workers,  since  less  than  l.ooo  parasites  of  this  species  had  been 
received  from  all  localities,  the  earlier  ones  having  come  from  southern 
Russia  and  from  Japan. 

The  winter  of  1908-9  was  spent  at  the  laboratory,  in  additional 
rearing  operations,  some  of  them  on  a  large  scale,  and  in  studying  the 
parasites  already  reared,  and  planning  for  the  coming  summer. 

As  it  happened,  during  the  winter  the  brown-tail  moth  was  intro- 
duced into  the  United  States  upon  nursery  stock  from  France  in 
huge  numbers.  Shipments  of  nursery  stock  bearing  whiter  nests 
of  this  insect  were  sent  to  many  States  of  the  I  nion.  Fortunately 
this  was  discovered  early  in  the  winter,  and  through  prompt  action 
and  the  cooperation  of  the  customs  officials  and  the  railroads  prob- 
ably every  sending  was  traced  to  its  ultimate  destination,  and  was 
t  here  inspected  and  the  nests  destroyed  either  by  State  officials  or  by 
persons  appointed  for  this  purpose  by  the  United  States  Department 
of  Agriculture. 

In  the  spring  of  1909  it  seemed  necessary  for  the  chief  of  the 
bureau  to  proceed  to  Europe  for  the  purpose  of  making  an  investi- 
gation of  the  European  methods  of  growing  nursery  stock,  witli  a 
view  to  the  prevention  of  similar  introductions  in  the  future  either 
by  general  legislation  by  the  United  States  Government  or  in  some 
other  way.  On  this  trip  he  utilized  the  opportunity  to  consult 
further  with  European  agents  in  the  importation  of  the  parasites 
and  to  arrange  for  the  summer's  work. 

In  the  meantime  Prof.  Kineaid,  whose  appointment  had  been  made 
by  the  State  of  Massachusetts,  and  who  had  again  been  made  an 


76  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

official  collaborator  of  the  Bureau  of  Entomology  of  the  United 
States  Department  of  Agriculture,  securing  leave  of  absence  from 
the  University  of  Washington,  proceeded  to  Russia,  and  stationed 
himself  in  Bessarabia  for  the  purpose  of  collecting  and  sending  para- 
sitized material  from  that  country  to  the  United  States.  It  had  been 
noticed  by  Mr.  Vuillet  at  Rennes  during  the  preceding  summer  that  all 
material  coming  from  Russia  had  been  opened  on  the  journey  and  had 
deteriorated  in  consequence.  Before  Prof.  Kincaid's  departure  from 
America,  Russian  officials  had  been  communicated  with  through 
correspondence  between  the  chief  of  the  Bureau  of  Entomology  and 
Prof.  Porchinsky,  of  the  ministry  of  agriculture,  and  also  directly 
between  the  United  States  Department  of  State  and  the  American 
ambassador  at  St.  Petersburg  through  the  instigation  of  the  honor- 
able the  Secretary  of  Agriculture.  The  United  States  Government 
was  assured  that  the  Russian  Government  would  welcome  the  expe- 
dition and  would  facilitate  the  sending  of  material  in  every  way 
possible. 

The  chief  of  the  bureau  landed  at  Cherbourg  May  12.  He  pro- 
ceeded immediately  to  Paris,  where  a  conference  had  been  arranged 
in  advance  with  M.  Oberthiir,  M.  Vuillet,  and  Mr.  Henry  Brown,  the 
latter  an  English  entomologist  resident  in  Paris.  At  this  conference 
it  was  decided  to  abandon  the  forwarding  laboratory  at  Rennes  and 
to  station  Mr.  Vuillet,  during  the  forwarding  season,  at  Cherbourg. 
He  was  instructed  to  engage  quarters  at  that  seaport  and  to  arrange 
for  cold-storage  facilities,  with  the  intention  that  shipments  from 
France,  Switzerland,  and  Italy  should  be  forwarded  to  him  to  be 
kept  in  cold  storage  until  the  date  of  sailing  of  vessels,  and  then 
should  be  transferred  to  the  cold  room  of  the  next  steamer,  thus 
practically  keeping  all  living  specimens  dormant  from  the  time  of 
arrival  in  Cherbourg  until  the  time  of  arrival  in  New  York,  making 
the  exposure  to  summer  temperature  practically  only  24  hours  or  less 
in  Europe  and  24  hours  or  less  in  the  United  States.  In  the  mean- 
time Mr.  Oberthiir  was  authorized  to  arrange  for  an  extensive  service 
in  the  south  of  France,  through  Mr.  II.  Powell,  of  Hyeres,  one  of 
the  agents  for  the  year  1906.  The  preparation  of  the  requisite  boxes 
was  intrusted,  as  in  previous  years,  to  the  superintendence  of  Mr. 
Oberthiir,  and  Mr.  Powell  was  authorized  to  engage  as  many  col- 
lectors as  the  materia]  would  seem  to  need,  with  full  instructions  as 
to  packing  and  shipping  to  Cherbourg. 

The  visitor  then  proceeded  to  Wageningen,  Holland,  where  he 
arranged  for  further  assistance  from  Prof.  Dr.  J.  Ritzema  Bos.  From 
there  lie  went  to  Hamburg,  where  he  arranged  with  the  American 
Express  Co.  to  care  for  shipments  coming  from  Germany,  Russia, 
and  Austria-Hungary,  arrangements  being  made  to  keep  the  material 
on  ice  until  the  next  steamer  should  sail,  and  in  case  of  the  breakage 


Bui.  91,  Bureau  of  Entomoiogy,  U.  S.  Dept.  of  Agriculture. 


Plate  III. 


Fig.  1.— Roadside  Oak  in  Brittany,  with  Leaves  Ragged  by  Gipsy-Moth  Cater- 
pillars.  (L.  O.  Howard,  June,  1909.)  (Original.) 


Fig.  2.— M.  Rene  Oberthur  (in  Center  ,  Dr.  Paul  Marchal  (at  Right.',  with  Road- 
side Oaks  (Behind)  Ragged  by  Gipsy-Moth  Caterpillars.  (L.  O.  Howard,  June, 
1909.)  (Original.) 


Bui.  91,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agriculture. 


Plate  IV. 


Fig.  2.— Packing  Parasitized  Caterpillars  at  Hyeres,  France,  for  Shipment  to 
the  United  States,  1909.  (Original.) 


NARRATIVE  OF  PROGRESS  OF  WORK. 


77 


or  other  bad  condition  of  packages  arrangements  were  made  with 
Dr.  L.  Reh,  of  the  Hamburg  Museum,  to  act  as  expert  adviser  of  the 
express  company. 

From  Hamburg  he  proceeded  to  Berlin  for  a  short  consultation 
with  Dr.  K.  Heymons,  and  thence  to  St.  Petersburg.  At  St.  Peters- 
burg lie  was  assured  by  Mr.  Montgomery  Schuyler,  the  secretary  of 
the  embassy,  that  all  arrangements  had  been  made  with  the  Russian 
Government,  and  the  same  assurance  was  given  by  Prof.  Porchinsky. 
The  Russian  officials  insisted  that  none  of  the  190S  packages  going 
out  of  Russia  had  been  opened  by  the  Russian  postal  authorities,  and 
stated  that  in  their  opinion  the  opening  must  have  been  done  at  the 
German  frontier  by  German  officials.  A  strong  letter  was  then  writ- 
ten to  the  Hof£  David  J.  Hill,  United  States  ambassador  to  Germany, 
reciting  the  facts,  dwelling  upon  the  importance  to  America  of  the-o 
importations,  and  urging  him  to  secure  from  the  German  Govern- 
ment orders  to  postal  officials  to  pass  without  opening  boxes  of  these 
parasites  addressed  to  the  American  Express  ( <>.  in  Hamburg.  1  ,atcr, 
in  Dresden,  a  reply  was  received  from  Ambassador  I Iill.  stating  that 
the  German  Government  consented  to  issue  the  necessary  instruc- 
tions, but  still  later,  in  Paris,  an  additional  communication  from  the 
ambassador  requested  detailed  information  as  to  the  points  on  the 

German  frontier  where  these  sendings  would  enter  the  Empire.  By 
telegraphic  communication  with  Prof.  Kincaid,  in  southern  Kussia, 

and  the  Austrian  agents,  this  information  was  furnished,  bul  there 

seems  >till  to  have  been  some  opening  of  the  Russian  boxes  with 
resulting  damage  to  their  contents. 

After  Russia,  Dresden,  Tefschen,  Vienna,  Budapest,  [nnsbruck, 
Zurich,  and  Paris  were  consecutively  visited,  and  agents  were 
instructed  concerning  the  new  arrangements  for  shipping  material. 
At  Innsbruck  the  visitor  met  lor  the  first  time  Prof.  K.  VY.  von  Dalla 
Torre,  the  author  of  the  great  catalogue  of  the  Ilvmenoptera  of  the 
world,  and  got  his  views  on  the  subject  of  the  parasitic  Ilvmenoptera 
and  their  practical  handling. 

From  Paris  he  took  a  trip  into  .Normandy  and  Brittany  with  Dr. 
Paul  Maivhal.  of  the  ministry  of  agriculture  of  France,  and  Mr.  Kene 
Oberthur,  for  the  pupose  of  examining  into  the  export  nursery  indus- 
try, and  at  the  same  time  witli  a  view  of  observing  gipsy-moth  and 
brown-tail  moth  conditions  in  that  part  of  France.  (See  PI.  ITT, 
tig.  2.)  It  transpired  that  both  of  the  injurious  insects  were  unusu- 
ally abundant  in  portions  of  this  territory,  and  by  good  fortune  a 
small  oak  forest  covering  some  hundreds  of  acres  was  found  not  far 
from  Nantes,  in  which  there  had  been  an  outbreak  of  the  gipsy-moth 
more  serious  than  either  Dr.  Marchal  or  Mr.  Oberthur  had  ever  seen 
or  had  ever  heard  of  in  France.  Practically  every  tree  was  defoli- 
ated (see  PI.  Ill,  fig.  1),  and  at  the  time  of  the  visit,  the  last  week 


78 


PARASITES  OF  GIPSY  AND  BROWX-TAIL  MOTHS. 


in  June,  the  larvae  were  about  full  grown  and  making  ready  to  spin. 
The  natural  enemies  of  the  gipsy-moth  were  not  abundant  in  this 
forest,  although  a  few  were  seen  on  trees  along  the  highway  in  this 
general  region.  Nevertheless  the  invariable  experience  in  Europe  is 
that  following  such  an  outbreak  as  this  parasites  congregate  in  the 
region  the  following  year  and  multiply  in  enormous  numbers.  The 
finding  of  this  area,  therefore,  seemed  fortunate,  since  during  the 
season  of  1910  it  seemed  probable  that  parasites  would  be  abundant 
at  that  point.  This  hope  was  not  fulfilled,  however,  and  in  1910 
practically  no  gipsy-moth  larvae  were  to  be  found  in  that  general 
region. 

In  the  meantime  the  honorable  minister  of  agriculture  for  Japan 
had  at  the  request  of  the  honorable  the  Secretary  of  Agriculture  of 
the  United  States  designated  Prof.  S.  I.  Kuwana,  of  the  Imperial 
Agricultural  Station  at  Tokyo,  to  be  the  official  representative  of  the 
Japanese  Government  in  the  parasite  work  to  be  carried  on  during 
the  spring  and  summer  of  1909,  and  to  conduct  his  operations  in 
cooperation  with  and  in  correspondence  with  the  chief  of  the  Bureau 
of  Entomolog}T  of  the  United  States  Department.  Prof.  Kuwana 
has  shown  himself  in  this,  as  in  his  previous  work,  a  man  of  extra- 
ordinary intelligence  and  activity,  and  has  sent  in  a  number  of  inter- 
esting and  valuable  lots  of  parasitic  material  which  were  received  at 
Melrose  Highlands  in  uniformly  good  condition.  This  was  due  to 
the  great  care  and  intelligence  shown  by  Prof.  Kuwana  in  its  collec- 
tion and  in  his  methods  of  packing  and  shipping. 

The  most  nearly  perfect  European  service  during  the  summer  of 
1909  was  secured  in  France,  owing  to  the  arrangement  made  at  the 
May  conference  in  Paris.  In  the  south  of  France  very  many  people 
were  employed  under  Mr.  Powell,  and  several  thousand  boxes  of  good 
material  were  received  at  the  parasite  laboratory  from  this  region. 
(See  PI.  IV,  fig.  2.)  In  quantity  it  exceeded  the  total  of  all  the 
importations  of  a  similar  character  made  since  the  inception  of  the 
work,  and  from  it  have  been  reared  a  greater  number  of  important 
tachinid  parasites  than  have  been  reared  from  all  other  importations 
of  similar  character  taken  together.  The  size  of  the  French  shipments 
is  largely  due  to  the  intelligent  energy  of  Mr.  M.  Dillon  (see  PI.  IV, 
fig.  1),  with  whom  the  bureau  was  placed  in  relations  by  Mr.  Powell. 

Quantities  of  miscellaneous  material  were  also  received,  as  for- 
merly, from  numerous  collectors  in  Germany,  Austria,  Italy,  Hol- 
land, Belgium,  and  Switzerland. 

Prof.  Kineaid's  account  of  his  Russian  observations  is  as  follows: 

At  the  request  of  Dr.  L.  O.  Howard,  Chief  of  the  Bureau  of  En- 
tomology, United  States  Department  of  Agriculture,  the  writer 
visited  the  provinces  of  Russia  bordering  upon  the  Black  Sea  during 
the  summer  of  1909  with  a  view  to  the  introduction  into  America 


NARRATIVE  OF  PROGRESS  OF  WORK. 


79 


of  the  parasites  of  the  gipsy  moth  reported  to  exist  in  that  part  of 
Europe.  Proceeding  to  St.  Petersburg  via  New  York  and  Paris,  an 
interview  was  had  with  Prof.  Porchinsky,  of  t ho  Russian  Bureau  of 
Entomology,  who  supplied  valuable  information  and  suggestions  for 
the  furtherance  of  the  investigation.  Leaving  the  Russian  capital 
on  April  28,  a  journey  of  48  hours  brought  the  writer  to  the  city  of 
Bjshenef  and  alter  making  a  survey  it  was  decided  to  establish 
a  base  of  operations  in  the  forest  of  Gauchesty,  an  area  of  wooded 
hills  adjacent  to  a  village  of  that  name  about  30  versts  1  northwest 
from  Kishenef.  Since  the  accommodations  in  the  village  of  Gau- 
chesty were  of  an  unsatisfactory  character,  Mr.  Artemy  Nazaroff, 
the  manager  of  the  estate  of  Prince  Manook  Bey,  on  the  lands  of 
which  the  more  important  infested  areas  existed,  invited  the  writer 
and  his  interpreter  to  become  his  guests  during  the  progress  of  the 
investigation.  A  suite  of  rooms  in  the  gue>t  house  of  Gauchesty 
castle  was  placed  at  our  disposal,  and  Mr.  Xazarolf  did  all  in  his 
power  t<>  forward  our  interests  and  to  make  agreeable  our  stay  in 
that  part  of  Russia.  An  outbuilding  upon  the  farm  of  the  estate 
was  transformed  into  a  laboratory  in  which  was  erected  a  set  of 
reining  frames  for  the  rearing  of  the  parasites.  During  the  first 
week  of  April  systematic  exploration  of  tin*  adjacent  wooded  areas 
w  as  begun.  The  forest  cover  was  found  to  consist  almost  exclusively 
of  young  oaks,  with  a  few  scattering  trees  of  other  species.  The 
ground  beneath  the  trees  was  fairly  tree  from  underbrush  and  was 
carpeted  with  a  rich  profusion  of  shrubs  and  flowers.  At  a  distance 
of  7  versts  from  Gauchesty  w  as  an  area  covered  with  trees  of  con- 
siderable age  among  which  the  underbrush  was  comparatively  dense. 

From  the  forester  in  charge  of  the  timbered  areas  upon  the  estate 
it  was  learned  that  the  gipsy  moth  had  done  great  damage  to  the 
forest  during  the  previous  season,  large  areas  having  been  completely 
defoliated.  This  statement  was  borne  out  by  the  immense  number 
of  egg  masses  attached  to  the  trees.  At  the  time  we  commenced 
our  investigations  the  caterpillars  had  emerged  from  the  eggs  but 
were  still  resting  upon  the  bark.     Kew  signs  of  previous  parasitic 

activity  were  observed  beyond  the  discovery  of  a  number  of  empty 

cocoons  of  Apttntths  solihirius  Katz.  attached  to  the  bark  of  the 
trees.  In  the  ancient  forest  mentioned  above  the  egg  masses  were 
very  numerous,  but  the  number  of  larvae  upon  the  bark  w  as  remark- 
ably small.  From  the  abnormal  appearance  of  most  of  these4  egg 
masses,  and  from  the  fact  that  several  Microhymenoptera  were  dis- 
covered in  them,  it  seemed  probable  that  a  considerable  number  of 
the  eggs  bad  been  destroyed  through  this  agency.  In  other  parts  of 
the  forest  no  evidence  \vas  secured  indicating  the  presence  of  egg 
parasites. 

The  brown-tail  moth  seemed  to  be  practically  absent  from  the 
forested  areas,  but  in  the  open  rolling  country  between  .Kishenef  and 
Gauchesty  many  wild  pear  growing  in  cultivated  fields  were  found 
to  be  completely  defoliated.  A  large  number  of  the  larvae  were 
placed  in  rearing  frames  but  yielded  no  parasites,  not  even  Meteorus 
making  its  appearance. 

By  June  1  the  caterpillars  of  the  gipsy  moth  had  passed  into  the  . 
second  stage  and  the  oak  trees  were  showing  obvious  signs  of  damage, 
but  up  to  this  date  there  was  no  indication  of  the  emergence  of 


1  Verst:  Russian  measure  of  distance=3,500  English  feet;  G  versts=approxiinately  4  English  miles. 


80 


PARASITES  OF  GIPSY  AND  BROWX-TAIL  MOTHS. 


hymenopterous  parasites  either  in  the  field  or  from  the  thousands  of 
larva?  reared  in  rearing  frames.  It  became  apparent  that  the  con- 
ditions were  unfavorable  for  the  purposes  in  mind  of  assembling 
parasites  for  export,  and  it  was  decided  to  shift  our  headquarters  to 
a  more  promising  locality. 

On  June  5  a  new  base  of  operations  was  established  at  the  town 
of  Bendery  on  the  Dniester  River.  Quarters  were  selected  in  the 
principal  hotel,  the  Petersburgia,  and  in  a  remote  corner  of  the  exten- 
sive grounds  of  the  hostelry  a  temporary  laboratory  was  constructed 
in  which  several  tiers  of  rearing  frames  were  erected.  The  forest 
conditions  in  this  district  were  much  more  diversified  than  at  Gau- 
chesty.  To  the  northeast  of  the  town  at  a  distance  of  7  versts  was 
the'  forest  of  Gerbofsky,  occupying  a  dry  elevated  area  of  about 
5,000  acres  and  consisting  almost  exclusively  of  mature  oak  trees. 
To  the  southward,  on  the  banks  of  the  river,  was  the  forest  of  Kitz- 
kany,  composed  largely  of  black  poplar,  maple,  and  willow.  In  both 
of  these  forests  the  caterpillars  of  the  gipsy  moth  were  found  in 
immense  numbers,  and  evidence  of  attack  by  both  hymenopterous 
and  dipterous  parasites  was  readily  obtained,  although  nowhere  in 
the  abundance  hoped  for.  For  two  weeks  the  two  forests,  as  well  as 
the  extensive  orchards  in  the  vicinity  of  Bendery  and  the  neighboring 
town  of  Tiraspol,  were  scoured  for  parasites.  A  number  of  Russian 
boys  were  pressed  into  service  and  trained  to  assist  in  making  collec- 
tions, at  which  they  became  quite  expert.  Except  for  a  few  clusters 
of  cocoons  derived  from  Apanteles  fulvipes  Hal.,  the  only  hymenop- 
terous parasite  to  appear  in  considerable  abundance  was  Apanteles 
solitarius.  Caterpillars  of  the  gipsy  moth  attacked  by  this  species 
crawl  down  to  the  trunk  or  lower  branches  of  the  tree  and  collect  in 
colonies  on  the  lower  side  of  the  branches,  under  bark,  in  cavities 
and  other  sheltered  places.  Here  the  larva  of  the  parasite  emerges 
and  spins  its  cocoon  beneath  the  body  of  its  host.  The  task  of  col- 
lecting these  scattered  cocoons  was  a  tedious  one,  since  it  was  neces- 
sary to  remove  each  one  carefully  from  the  bark  without  undue 
pressure  and  also  to  disentangle  it  from  the  hairy  body  of  its  host. 

In  the  forest  of  Kitzkany,  where  the  conditions  were  favorable  for 
bacterial  infection  owing  to  excessive  dampness,  the  caterpillars  of 
the  gipsy  moth  were  swept  away  in  vast  numbers  by  a  bacterial 
disease  before  any  extensive  defoliation  took  place.  .  The  search  for 
hymenopterous  parasites  in  this  district  soon  become  a  vain  one, 
since  very  few  of  the  caterpillars  appeared  to  have  escaped  the 
infection. 

The  forest  of  Gerbofsky,  owing  to  its  being  elevated,  open,  and 
well  drained,  was  not  favorable  for  bacterial  infection  and  no  trace 
of  disease  was  observed.  This  forest  was  therefore  almost  com- 
pletely defoliated  by  the  caterpillars,  and  multitudes  of  the  insects, 
failing  to  find  any  further  nourishment  upon  the  oaks,  descended  to 
the  ground,  where  they  died  in  great  numbers,  apparently  from 
starvation.  Hymenopterous  parasites  seemed  to  play  a  relatively 
small  part  in  the  destruction  of  the  caterpillars,  since  the  attacks  of 
AjHinielcH  so/.Jfarius  were  of  the  most  scattering  character.  In  the 
shrubbery  growths  adjacent  to  the  main  forest,  where  new  planta- 
tions had  been  recently  established  by  the  forester  in  charge,  a  con- 
siderable number  of  Calosoma  were  found  at  work  destroying  the 
caterpillars,  but  their  operations  did  not  appear  to  extend  into  the 


NARRATIVE  OF  PROGRESS  OF  WORK. 


81 


main  forest,  where  the  open  grass-covered  ground  did  not  offer  suf- 
ficient concealment  for  the  beetles. 

Thje  principal  check  to  the  depredations  of  the  caterpillars  of  the 
gipsy  moth  in  this  forest  came  with  the  advent  of  the  tachinids,  the 
latter  appearing  upon  the  scene  after  the  trees  had  been  almost  or 
entirely  defoliated.  Chalcid. flies  also  appeared  at  this  time,  but  not 
in  considerable  numbers.  The  species  of  Limnerium,  a  few  speci- 
mens of  which  had  been  previously  received  from  Russia,  and  of 
which  it  had  been  hoped  to  secure  a  supply  for  transfer  to  America, 
proved  to  be  exceedingly  rare,  only  three  specimens  being  found. 
The  larva  of  this  parasite  on  emerging  from  its  host  spins  an  elongated 
silken  thread,  at  the  end  of  which  it  spins  a  cocoon  and  transforms 
to  the  pupal  state. 

Considerable  numbers  of  the  cocoons  of  Apantdi*  solitariua  were 
collected  from  the  forest,  from  the  extensive  orchards  of  the  neigh- 
borhood, and  from  clumps  of  willow  bushes  conmonly  found  at  the 
edges  of  fields.  For  several  weeks  shipments  were  made  almost 
dally  to  Hamburg,  from  which  port  the  packages  were  shipped  in 
cold  storage  to  New  York.  Many  difficulties  arose  til  attempting  to 
make  rapid  shipments.  The  postal  connections  were  very  unsatis- 
factory and  caused  annoying  delays,  while  at  the  German  frontier 
another  cause  for  loss  of  time  developed  through  the  formalities  of 
the  customs  authorities  of  the  German  Government. 

The  brown-tail  moth  seemed  to  be  quite  uncommon  in  the  region 
about  Bendery,  and  no  parasites  were  observed  upon  the  small  num- 
ber of  larva'  collected  at  this  point. 

Since  it  seemed  desirable  to  cover  as  extensive  a  territory  as  pos- 
sible during  the  season,  the  writer,  leaving  an  assistant  in  charge  of 
the  laboratory  and  collecting  organization  at  Bendery,  journeyed 

northward  on  dune  17  and  established  a  aew  center  of  exploration  at 

the  city  of  Kief,  in  the  province  of  the  same  name.  Through  the 
courtesy  of  Prof.  YValdeniar  Pospielow  the  writer  was  furnished  with 
much  valuable  information  in  regard  to  the  forests  of  this  portion  of 
Russia  and  concerning  the  areas  in  which  the  gipsy  moth  was  known 
to  exist.  SeveraJ  immense  forested  areas  were  traversed,  but  as  they 
were  for  the  most  part  purely  coniferous  in  character  the  gipsy  moth 
appeared  to  be  quite  a  rare  insect.  Through  information  supplied 
by  Prof.  Pospielow  it  was  ascertained  that  at  Mechnigori,  a  nionas- 
terial  institution  on  the  banks  of  the  Dnieper,  several  hours  by 
steamer  from  Kief,  an  area  of  woodland  existed  which  was  infested 
to  a  m<  derate  extent  by  caterpillars  of  the  gipsy  moth,  among  which 
the  parasites  were  reported  to  be  much  in  evidence.  A  visit  to  the 
locality  showed  an  interesting  condition.  The  monastery  was  sur- 
rounded by  beautiful  groves  of  elm  and  oak  trees  in  which  the  gipsy 
moth  had  made  considerable  inroads,  but  the  parasites  had  developed 
to  a  sufficient  extent  to  practically  clear  the  foliage  of  caterpillars. 
Almost  the  sole  agency  in  bringing  about  this  condition  was  Apon- 
teles  rujijH'S,  which  attacks  the  larvae  of  the  gipsy  moth  in  a  manner 
closely  resembling  Apanteles  japonicus,  as  observed  during  the  pre- 
ceding season  in  Japan,  but  in  the  case  of  the  latter  the  caterpillars 
usually  die  upon  the  leaves  of  the  trees,  whereas  in  the  former  the 
caterpillars  descend  to  the  trunk  and  lower  branches  to  form  colonies. 
On  emerging  from  the  caterpillars  the  parasites  spin  cocoons  beneath 


05<;7 7°— Bull.  01—11  6 


82 


PAEASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


the  host,  which  are  also  attached  ventrally  to  the  bark  of  the  tree, 
and  as  numerous  caterpillars  die  in  a  restricted  area  a  mass  of  Apan- 
teles  cocoons,  often  of  considerable  thickness,  is  formed.  Such 
masses  standing  out  as  white  patches  against  the  dark  tree  trunks  on 
which  they  rest  may  be  seen  for  considerable  distances.  Cocoons  of 
Apantales  sol'darius  were  also  observed  in  the  forest  of  Mechnigori, 
but  were  comparatively  rare,  so  this  species  evidently  did  not  repre- 
sent a  very  important  element  in  the  control  of  the  gipsy  moth. 

In  the  forested  areas  about  Kief  the  caterpillars  of  the  brown-tail 
moth  were  rarely  met  with,  but  in  several  of  the  parks  on  the  out- 
skirts of  the  city  they  were  found  in  abundance.  In  the  grounds  of 
the  military  school  a  large  number  of  magnificent  oak  trees  were 
almost  denuded  of  foliage,  and  some  of  the  other  deciduous  trees  and 
shrubs,  such  as  poplars,  rose  bushes,  and  Crataegus,  were  severely 
damaged.  The  usual  brown-tail  parasites  were  found  at  work,  the 
most  effective  being  Meteorus.  Almost  every  branch  of  the  injured 
trees  bore  the  suspended  cocoons  of  this  parasite.  Tachinids  were 
also  active,  so  it  was  obvious  that  very  few  of  the  caterpillars  would 
reach  maturity. 

On  departing  from  Kief  on  July  9  the  season  was  practically  over, 
and  gipsy  moths  were  in  flight. 

Returning  to  Bendery,  it  was  found  that  the  season  was  over  so  far 
as  Apantales  sol'darius  was  concerned,  but  large  numbers  of  tachinid 
puparia  were  in  evidence.  As  many  as  possible  of  these  were  assem- 
bled and  shipped  to  America.  The  chrysalides  of  the  gipsy  moth 
were  also  forwarded  in  considerable  numbers  in  the  hope  of  securing 
pupal  parasites. 

These  lines  of  work  were  continued  till  July  16,  by  which  time  the 
season  was  so  advanced  that  the  moths  were  beginning  to  deposit  their 
eggs  for  the  succeeding  season.  From  the  abundance  of  moths  in 
flight  it  was  obvious  that  unless  the  natural  parasites  multiplied  suf- 
ficiently to  control  the  situation  the  region  would  experience  another 
visitation  of  the  same  character  during  the  following  year. 

Leaving  Bendery  on  July  16,  the  writer  returned  to  Paris  via 
Odessa,  Constantinople,  and  Naples,  arriving  in  New  York  August  28. 

Owing  to  various  unforeseen  conditions,  and  principally  owing  to 
the  deficient  transportation  facilities,  the  material  received  as  the 
result  of  Prof.  Kincaid's  expedition  proved  to  be  unsatisfactory  on 
the  whole. 

In  May  and  June,  1910,  the  senior  author  went  to  Europe  once 
more,  visited  agents  and  officials  in  Italy  and  France,  and,  through 
the  courtesy  of  the  Spanish  and  Portuguese  Governments,  was  able 
to  start  new  official  services  in  each  of  these  countries  for  the  collec- 
tion and  sending  of  parasitized  gipsy-moth  larvae  to  the  United 
States.  In  Italy  Prof.  Silvestri  at  Portici  and  Dr.  Berlese  at  Flor- 
ence were  visited  and  informed  as  to  the  latest  ideas  of  the  laboratory 
regarding  methods  of  shipment.  In  Spain  Prof.  Leandro  Navarro, 
of  the  Phytopathological  Station  at  Madrid,  volunteered  his  services 
with  the  approval  of  the  minister  of  agriculture.  In  Portugal  Senhor 
Alfredo  Carlos  Lecocq,  director  of  agriculture,  placed  the  visitor  in 
relation  with  Prof.  A.  V.  de  Seabra,  of  the  Phytopathological  Station 


NARRATIVE  OF  PROGRESS  OF  WORK. 


83 


at  Lisbon,  and  the  latter  gladly  consented  to  act  as  the  agent  of  the 
bureau  in  this  work  in  Portugal.  In  France  arrangements  were  made 
with  Mr.  Dillon  as  during  the  previous  year  in  the  south  of  France, 
and  arrangements  were  renewed  with  Miss  Ruhl  in  Zurich  and  Mr. 
Schopfer  in  Dresden.  The  distributing  agency  in  Hamburg  was  con- 
tinued, and  a  new  distributing  agency  was  started  at  Havre,  France, 
on  account  of  its  convenient  proximity  to  the  American  line  steamers 
starting  from  Southampton.  In  order  to  insure  the  best  results,  Mr. 
Dillon  accompanied  certain  large  shipments  from  Ilveres  to  Havre, 
and  personally  saw  that  they  were  placed  upon  the  channel  steamer 
the  night  before  the  sailing  of  an  American  line  steamer  from 
Southampton. 

Sendings  from  Japan  were  continued  in  the  same  manner  as  dur- 
ing the  previous  year.  The  minister  of  agriculture  for  Japan,  at  the 
request  of  the  Secretary  of  Agriculture  of  the  United  States,  again 
designated  Prof.  S.  I.  Ivuwana,  of  the  Imperial  Agricultural  Experi- 
ment Station  at  Tokyo,  to  be  its  official  representative  in  this  work, 
and  he  continued  his  extremely  valuable  sendings. 

The  amount  received  during  the  summer  was  larger  than  ever 
before,- but  the  results  obtained,  ow  ing  partly  to  the  condition  of  the 
material  on  receipt  and  owing  to  curious  seasonal  fluctuations  and 
differences  in  the  countries  of  origin  and  in  the  infested  territory  in 
America,  the  results  by  n<>  means  corresponded  with  the  increased 
material.  The  work  carried  <>n  in  the  laboratory  during  the  season 
and  the  results  obtained  are  mentioned  later. 

In  the  autumn  the  junior  author  visited  France  and  Russia  for  the 
purpose  of  studying  certain  important  points  regarding  the  question 
of  alternate  hosts  of  the  parasites  and  methods  of  hibernation.  The 
results  of  his  observations  will  be  given  in  detail  in  the  later  section 
headed  "The  extent  to  which  the  gipsy  moth  is  controlled  through 
parasitism  abroad." 

At  the  close  of  the  season  of  1 1)1 0,  and  in  part  owing  to  the  prepara- 
tion of  the  present  bulletin,  a  general  review  of  the  whole  work  was 
undertaken,  and  a  summing  up  of  present  conditions  seemed  to  indi- 
cate that  nearly  as  much  had  already  been  accomplished  by  present 
methods  as  could  be  expected.  The  great  need  at  this  time  seemed 
to  be  a  careful  study  in  the  countries  of  origin  of  the  species  of  appar- 
ent importance  which  have  been  >ent  over  but  have  not  become 
established,  in  order  to  ascertain  the  reasons  for  the  apparent  failure; 
and,  further,  to  see  on  the  spot  what  can  be  done  with  regard  to  the 
importation  of  parasites  of  apparently  lesser  importance,  but  which, 
through  the  fact  that  they  may  fdl  in  gaps  in  the  parasitic  chain  and 
may  at  the  same  time  increase  beyond  their  Dative  wont  when  con- 
fronted with  American  conditions,  may  be  very  desirable.  Accord- 


84  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

ingly  the  junior  author  was  commissioned  to  visit  France,  Italy,  and 
Russia  in  the  winter  and  early  spring  of  1911,  and  subsequently  to 
spend  the  breeding  season-  if  found  desirable,  in  Japan.  He  was 
given  authority  to  employ  the  necessary  agents  in  each  of  these  coun- 
tries.   He  sailed  January  5,  1911. 

KNOWN  AND  RECORDED  PARASITES  OF  THE  GIPSY  MOTH  AND  OF 
THE  BROWN-TAIL  MOTH. 

When  the  work  of  introducing  the  parasites  of  the  gipsy  moth  and 
of  the  brown-tail  moth  was  begun  in  1905,  the  available  assets  con- 
sisted of  generous  appropriations  by  the  State  of  Massachusetts  -and 
the  Federal  Government,  an  abundant  faith  in  the  validity  of  the 
theory  which  was  to  be  put  to  test,  and  a  long  bibliographical  list 
of  the  parasites  which  were  recorded  as  attacking  these  insects  in 
Europe  and  Japan.  Of  these,  the  appropriations  have  withstood 
most  effectively  the  ordeal  of  the  years  which  have  since  passed. 
Our  faith  in  the  validity  of  the  principle  at  stake  has  also  stood  out 
wonderfully  well,  when  the  numerous  trials  to  which  it  has  been 
subjected  are  taken  into  consideration.  It  is  not  too  much  to  say 
that  at  the  present  time  it  is  stronger  than  ever,  notwithstanding 
that  a  good  many  facts  have  come  to  light  in  this  period  which -are 
more  or  less  flatly  in  contradiction  to  the  theory  of  parasite  control 
as  generally  accepted  at  the  beginning.  It  has  more  than  once  been 
necessary  to  modify  beliefs  and  ideas  as  previously  held,  in  order  to 
make  them  conform  to  the  actual  facts.  To  take  a  pertinent  exam- 
ple, it  was  necessary  to  place  an  entirely  different  value  upon  the 
bibliographical  list  above  mentioned  than  that  which  was  placed  upon 
it  when  the  work  was  begun,  and  when  the  policies  of  the  laboratory 
were  first  determined. 

Nearly  thirty  years  ago  the  present  head  of  the  Bureau,  of  Ento- 
mology undertook  the  compilation  of  a  card  catalogue  of  references 
to  the  host  relations  of  the  parasitic  Hymenoptera  of  the  world. 
For  more  than  twenty  years  the  work  was  continued  until  some 
30,000  such  references  were  accumulated.  From  among  them  those 
in  which  the  gipsy  moth  was  mentioned  as  the  host  were  collected 
and  a  list  of  gipsy-moth  parasites  was  published  in  Insect  Life.1 
With  the  exception  of  a  comparatively  few  recent  additions  this  list 
forms  the  basis  of  that  which  follows.  That  of  the  parasites  which 
have  been  recorded  as  attacking  the  brown-tail  moth  is  largely  from 
the  same  source. 


1  U.  S.  Department  of  Agriculture,  Division  of  Entomology,  Insect  Life,  vol.  2,  pp.  210-211,  1890. 


KNOWN  AND  RECORDED  PARASITES. 


85 


HYMEN*  )PTEROUS  PARASITES  OF  THE  GIPSY  MOTH  (Porthetria  dispar  L. ,. 

Bracoxid.e. 


Reared  at  laboratory. 
Apantele8 fulvxpes  (Hal.). 
Apantehs  solitarius  I  Rai  / 


Meteorus  versicolor  (Wesm.). 
Mi  tiorus  pulchricornis  i  W»-sin. t. 
Meteorus  japonicus  Ashm.3 


Recorded  as  parasites. 
Apantehs  f/lvipes  (Hal.).  1  2 
Apantehs  sohtarius  |  Rats.)'1  2 
Microgaster  calccata  Hal.1  2 
Apantelcs  tcnebrosus  (Wesm.).1 
Microgaster  tibialis  'Sees.1 
(  Microgaster)  Apantths  fulvxpes  liparidis 

(Bouchej.1  2 
Apanleles  glomeratus  (L.).1  2 
Apantehs    se>litarius    var.  mtlanosctlus 

(Ratz.).1 

Apantths  solitarius?  ocncriie  Svanov. 
MeJeonu  teutellator  I  Nees).1 


ICHS  KI  \1<  >\  1 1 '. V. . 


TRIM  A  I  V. 


Pimpla    Pirn  pin)  instigator  i  Fab. ». 
Piitipln  (  Pimpla)  porthetri.i  \'icr.! 
Pimpla  (Pimpla)  ermninator  (Fab.). 
Pimpla  i  Pimpla   pinto  \A\u\.  '■ 
Pimpla  i  Apichtlus    brassirari:i  <  P« »<l:i  i . 
Pimpla    Pimpla)  disparis  Yier.1 
Theronia  atalantx  (Poda). 
Limnt  fin  m  i  Ifi/pnsotiri  disparis  Yirr. 
Limtu  rinm  i  Anilastus  i  tricolor! pi  s  \"wr. 
7r/</<<  /////o?i  disparis  i  Poda  >. 


Pimpla  (Pimpla)  instigator  |  Fab.).1  2 
Pimjda  e.raminnfor  (Fab.).1 


Theronia  atalant.t  i  Poda).1  2 

Campoph  r  amicus  Ratz.1 

Casinuria  U  nuivt  ntris  (Grav.).1 

7r/</i<  i/Hiod  disparis  i  Poda).1  2 

Ichneumon  pictus  (Gmol.).1  2 

Amfilij/ilis  niripes  Rd\V.2 

'Prog us jlai  itorius  [sic]  luforius  i  Fab.  i?  1  2 

{('ryptusi  Aritranis  anmnus  ((irav.).1 

Cnjplus  cganator  Grav.1 


riiiiHAHI  V  sK.roNHAUY  BI  T  KKCOHDBD  AS  PRIM  A  K  Y. 


Mi  socftorus  p<  floral  is  Ratz.1  2 
Mesochorus  gracilis  Rrischke.1  2 
Mesochorus  sph  ndidulns  (irav.1  2 
Mi  sochorus  confusus  Hoi  mgr.1 
Mesochorus  semirufus  Ilolmgr.1 
(Hemitehs)  Astomaspis  f id vipes  (Grav.).1  2 
=  .4.  nanus  (Grav.  )  according  to  Pfan- 
kuch. 

Hcviiteles  bicolorius  Grav.3 
Pczomachus  hortensis  Grav.2 
Pezomachus  fascial  us  (Fab.)  l=Pezomachus 
melanoccphalus  (Schrk.). 

1  Recorded  by  the  senior  author  in  a  card  catalogue  of  parasites  kept  in  the  Bureau  of  Entomology. 
s  Recorded  by  Dalla  Torre  in  Catalogus  Hymenopterorum. 
i  Japanese  species. 


86 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Chalcidid^e. 


Reared  at  laboratory. 


Eupelmus  bi/asciatus  Fonsc. 
Monodontomerus  sere  us  Walk. 
Chalcis  flavipes  Panz. 
Chalets  obscurata  Walk.4 
Schedius  kuranx  How.4 


Recorded  as  parasites. 
Pteromalus  halidayanus  Ratz.1 
Pteromalus  pini  Hartig.1 
Dibrachys    boucheanus  Ratz.1 

ary-) 

Eurytoma  abrotani  Panzer  1  : 

gaster  Swed.  (Secondary.) 
Eupelmus  bi/asciatus  Fonsc.1  2 

Chalcis  callipus  Kby.3 


(Second- 
-appendi- 


HYMENOPTEROUS  PARASITES  OF  THE  BROWX-TAIL  MOTH  (Euproctis 

chrysorrhcea  L.). 


Reared  at  laboratory 
Meteorus  versicolor  (Wesm.). 

Apanteles  lacteicolor  Yier. 


Bracoxid.e. 


Recorded  as  parasites. 
Meteorus  versicolor  (Wesm.).5 
Meteorus  ictericus  (Nees).5 
Apanteles  inclusus  (Ratz.)  2  5 
Apanteles  ultor  Reinh.1  2  3 
Apanteles  difficilis  (Nees).5 
Apanteles  liparidis  (Bouche).5 
Apanteles  vitripennis  (Hal.).5 
Apanteles  solitarius  (Ratz.).5 
Mu  rogaster  consulans  (Hal.)  5 

ter  connexa  Nees. 
Microgaster  calceata  Hal.1 
Rogas  geniculator  Nees.2  5 
Rogas  testaccus  (Spin.).1 
Rogas  pulchnpes  (Wesm.).1 


Microgas- 


ICHXEl'MOXID.K. 


PRIMARY. 


Pimpla  (Pimpla)  exawinator  (Fab.). 
Pimpla  (Pimpla)  instigator  (Fab.). 
Pimpla  (Apechthis)  brassicarix  (Poda). 
Theronia  atalantx  (Poda). 


Pimpla  (Pimpla)  examinator  (Fab.).2  5 
Pimpla  (Pimpla)  instigator  (Fab.).1  2  3 

Theronia  atalantx  (Poda).1  2  3 
Campoplex  conicus  Ratz.5 
(Campoplex)  Omorgus  dijformis  (Gmel.).5 
Crypt  us  moschator  (Fab.).1 
(Cryptus)  Idiolispa  atripes  (Grav.).1 
Ichneumon  disparis  (Poda).5 
Ichneumon  scutellator  (Grav.).2 


1  Recorded  by  the  senior  author  in  a  card  catalogue  of  parasites  kept  in  the  Bureau  of  Entomology. 

2  Reconled  by  Dalla  Torre  in  Catalogus  Ilymenopterorum. 
s  Reared  by  Dr.  S.  I.  Kuwana. 

*  Japanese  species. 
Recorded  by  Emelyanoif. 


KNOWN"  AKD  RECORDED  PARASITES. 


87 


PROBABLY  SECONDARY,  BUT  RECORDED  AS  PRIMARY. 

Reared  at  laboratory.  Recorded  as  parasites. 

}ftsochorits  pcctoralis  Ratz.1  2  3 
Mcsochorus  dilutus  Ratz.2  3 
Ilemitihs  socialis  Ratz.3 

Cha&CEDIDjB. 

Pteromabis  sp.  Pteromatus  rotundatus  Ratz.3=Pf.  chry- 

sorrhaa  D.  T.1  2 

I'f>  mmalus  nidulans  Thorns.  =  Pt .  ujmjius     Pliromahis  proccssio7U\r  Ratz.1  2 
Forst. 

Diglochis  omnivora  Walk.  Ptiromalus  nidulans  Thorns.1  3 

Pt*  mmalus  puparum  L.3 
Dibrachys  boucheanui  (Ratz.).3  (Second- 
ary.) 

( 'halcis  scirmpoda  Forst.1 
Monodontmm  rus  n  r,  us  W  alk.  Tnnjin  us  am  pin  his  Kat  z.3  =  Monodontomc- 

ms  irn  us  Walk.1  1 
Mnnixlontoiin  rus  dnfipis  Boh.1  2 
Anagrut  oi  ivonu  Romlani.2 

Trichujramma  sj>.  I. 
Trithogra mma  s\>.  II. 

Proctotrypio  m. 

Tib  nonius  phahrnarum  Nee8  (?).  Tihnomus  phalu  narum  Xeos.1  2  3 

IHPTKROIS   IWRASITKS  ()F  TIIK  UIPSY   MOTH    (Pnrtlutnn  dispar  L.). 

The  following  are  lists  of  the  dipterous  parasites  reared  and 
recorded  from  Porthetria  dispar  L  and  Eu proctis  chrysorrhcea  L.  Each 

list  is  supplemented  by  a  list  of  recorded  hosts  for  each  species 
enumerated. 

These  lists  have  been  compiled  from  various  sources,  the  principal 
heim:  the  ' '  Kat aloLT  der  Palaarktischen  Dipteren,"  Brauer  &  Bergen- 
stamm's  "Die  Zweiflugler  des  Kai>erlichen  Museums  ZU  AYicn,"  Fer- 
nald  and  Forhush's  ''The  Gipsy  Moth. "  and  the  senior  author's  "List 
of  parasites  bred  from  imported  material  during  the  year  1907" 
(3d  annual  report  of  the  superintendent  for  suppressing  the  gipsy 
tand  brown-tail  moths). 

In  the  choice  of  names  of  the  foreign  tachinids  the  Katalosr  der 
Paliiarktischen  Dipteren  has  been  followed  with  the  exception  of  a 
few  cases  in  which"  other  names  have  been  in  use  at  the  Gipsy  Moth 
Parasite  Laboratory;  in  these  few  cases,  to  avoid  confusion,  no 
change  has  been  made. 

1  Recorded  by  Emelyanoff. 

1  Recorded  by  Dalla  Torre  in  Catalogus  Hyrnenopterorum. 

3  Recorded  by  the  senior  author  in  a  card  catalogue  of  parasites  kept  in  the  Bureau  of  Entomology. 


88 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Foreign  Tachinid  Parasites  on  Porthetria  dispar. 


Reared. 


Recorded. 


Blepharipa  scutellata  R.  D. 
Carcelia  gnava  Meig. 
Com psilura  concinnata  Meig. 
Crossocosmia  sericarix  Corn. 
Dexodes  nigripes  Fall. 
Parasetigena  segregata  Rond. 
Tachina  larvarum  L. 
Tachina  japonica  Towns. 
Tricholyga  grandis  Zett. 
Zygobothria  gilva  Hartig. 


Argyrophylax  atropivora  R.  D. 
Carcelia  excisa  Fall. 
Compsilura  concinnata  Meig. 
Echinomyia  /era  L. 
Epicampocera  crassiseta  Rond. 
Ernestia  consobrina  Meig. 
Eudoromyia  magnicornis  Zett. 
Exorista  affinis  Fall. 
Histochxta  marmorata  Fab. 
Lydella  pinivorx  Ratz. 
Meigenia  bisignata  Schin. 
Parasetigena  segregata  Rond. 
Phryxe  erythrostoma  Hartig. 
Ptilotachina  larvincola  Ratz. 
Ptilotachina  monacha  Ratz. 
Tachina  larvarum  L. 
Tachina  noctuarum  Rond. 
Zenillia  libatrix  Panz. 
Zygobothria  gilva  Hartig. 
Zygobothria  bimaculata  Hartig. 


N.  B. — It  is  interesting  to  note  that  only  four  species  are  common  to  both  lists. 
Recorded  Hosts  of  Foreign  Tachinid  Parasites  of  Porthetria  dispar  Reared 


Blepharipa  scutellata  R.  D.: 

Acherontia  atropos  L.;    Vanessa  antiopa  L. 
Carcelia  gnava  Meig.: 

Miilacosoma  neustria  L.;  Orgyia  antiqua  L.;  Stilpnotia  salicis  L. 
Compsilura  concinnata  Meig.: 

See  list  of  recorded  parasites  of  P.  dispar 
Crossocosmia  sericarle  Corn.: 

Antherxa  yamamai  Guer.;  A.  mylitta  Moore;  Sericaria  niori  L. 
Dexodes  nigripes  Fall.: 

Ascometia  caliginosa  Hb.;  Agrotis  candelarum  Stgr.;  Bupalus  piniarius  L.; 
Cucullia  asteris  Schiff . ;  Deilephila  euphorbix  L. ;  Eurrhypara  urticx  L. ;  Heliothis 
Si  utosa  Schiff.;  Ilybernia  sp.;  Mamestra  pisih.;  Miana  literosa  Hw . ;  Ortholitha 
cervinata  Schiff.;  Phragmatobia  fuliginosa  L.;  Plusia  gamma  L.;  Porthesia 
similis  Fusel.;  Tapinostola  elymi  Tr.;  Tephroclystia  virgauriata  Dbld.;  Thau- 
metopcea  pinivora  Tr.;  Vanessa  io  L.;  V.  polychlorus  L.;  V.  urticx  L.;  Lophyrus 
sp.;  Nematus  ribesii  Scop. 
Parasetigena  segregata  Rond. : 

(See  list  of  recorded  parasites  of  P.  dispar.) 
Tachina  larvarum  L.  : 

(See  list  of  recorded  parasites  of  P.  dispar.) 
Tachina  japonica  Towns.: 

/'orlhr/ria  <Iisj>ur  I.. 
Tricholyga  grandis  Zett. 

Arctia  caja  L.;   Mamestra  oleracea  L.J   M.  pisi  L.;  Saturnia  pavonia  L.;  *S\  pyri 
Schiff.;  Sphinx  ligusfril ,.;  Thaumetopwa  pilyocampa  Schiff.;  Vanessa  io  L. 


at  the  Gipsy  Moth  Parasite  Laboratory. 


KNOWN  AND  RECORDED  PARASITES.  89 

Recorded  Hosts  of  Foreign  Tachinid  Parasites  Recorded  on  Porthetria 

dispar. 

AltGYROPHYLAX  ATROPIVORA   R.  D.: 

/'.  dispar  L.J  Acherontia  atropos  L.J  Xotodonta  trepida  Esp.;    Vanessa  io  L. 
Carcelia  excisa  Fall.: 

Abrostola  tripartita  Hufn.;  A.  triplasia  L.;  Arctia  raja  L.;  A.  hebe  L.;  .1.  eillica 
L.;  Bupalus  piniarius  L.J  Callimorpha  do m inula  L.;  Cucullia  scrophularix 
Cap.;  Dasychira  pudibunda  L.J  Endromis  versicolora  L.;  Ilyloicus  pinastri  L.J 
I',  dispar  L.J  P.monacha  L.;  Malacosoma  castrcnsis  L.;  3/.  neustria  L.J  Orgyia 
antiqua  L.;  Phragmatobia  fuliginosa  L.J  Pterostoma  palpina  L.;  Pygiera 
curtula  L.J  Satumia  pyri  Schiff.;  Sphinx  ligustri  L.J  Stilpnotia  salicis  L.; 
Thalpochu  res  pannonica  Frr.;    Thaumetopa  a  ]>rocessionea  I.. 

(  nMPSILURA  CONCINNATA  Moig.: 

Abraxas  grossulariata  I-.;  Arronycta  aeeris  L.;  J.  n/m  L.;  .1.  ruspis  lib.;  J. 
n  >  (jacephala  F.j  .1.  rumicis  L.J  -1.  tridens  Schiff.;  Arasehinia  levana  L.;  ^4. 
prorsa  L.;  Arctia  raja  L.;  Attacns  rynthia  L.;  Cutocalu  promissa  Esp.;  Cranio- 
phora  ligustri  Fab.;  Cucullia  lactucr  Esp.;  r.  verbasei  K.;  Dasychira  pudibunda 
Dilinu  tilur  L.;  Dilobia  ncruleocephala  L.;  I)i pterygia  seabriuseula  L.; 
Drymonia  chaonia  Hl>.:  Euproctis  chrysorrhoa  L.;  Ilyloicus  pinastri  L.;  /,ify/- 
rr //As  Laich.;  Porthetria  dispar  L.;  /'.  moncha  L.;  Macrothylacia  rubi  L.; 
Maim  si  rii  firussir  i  I..;  M .  olerucca  \..\  .\f.  pcrsicari;c  I..;  Malacosoma  neustria  L.; 
(honis tii quadra  I..;  Phalera  buccphala  I..;  Picris  brassici  I..;  P.rup.r]..;  Plusia 
fistuci  I.  ;  /'  gamma  !..:  Pacelocam pa  populi  L.;  Porthesia  similis  Fiissl.; 
Pyg.ira  annchnrcta  Fab.;  Pyrameis  atulantu  L.;  Smerinthus  populi  L.;  Spilo- 
soma  lubricipi  da  L.;  N.  mcnthustri  Esp.;  Stauro pus  fagi  E.;  Stilpnotia  salicis  I,.  ; 
T;i  niocam pa  stubilis  View.;  Thaumetopaa  processioned  I..;  7'.  pityocampa 
Schiff.;  Timandrn  amata  L.;  Trachea  atri plicis  E.;  Er/mw/  antiopa  E. ;  E.  ioE.; 
V.  ur/lr.r  L.;  I'.  xunthomclas  Ksp. ;  Yponomeutn  padeila  E.;  Cimbcx  humeralis 
Pooler.;    Trichiocam pus  viminalis  Fall. 

EciIINOM  VIA    I  KK.V  I.. 

Agrntis  glarcosa  Ksp.;  Arctia  aulica  E.;  Leucania  obsoleta  Sb.;  Porthetria  dispar  E.; 
/'.  monacha  E.;  Maaiestra  }>isi  I..;  Otonistis  guudra  E.;  Panolis  grieovuriegata 
Goeze. 

Ki  n  am  roc  i  ka  ckassisi  ta  Rond.: 

Portia  trio  dispar  L.;    Thuunu  topo  a  proct  ssioma  L. 
Krnkstia  (on sou ki\ a  Mcig.: 

Cucullia  artemisi;e  Hilfll.;    Porthetria  dispar  I. 
Kcdoromyia  ma<;nicornis  Zctt.: 

Agrotis  sp.  i 1 1 <  1 . ;  m/  adusta  Esp.;  Porthetria  dispar  E. 

Exoris  a  akiinis  Fall.: 

Acnmycta  alni  L.J  .1/v/w  eaja  L.J  Porthetria  dispar  L.;  Pachytdia  eillosella  O .; 
Satumia  pavonia  L.J  5.  pyri  Schiff. 

HlsTOCH/ETA  MARMORATA  Fab.: 

J/v/mrajaL.;  il.gtMnJfZuPfcyk.;  A.  villica  ],.;  Cucullia  verbani  L.;  Malacosoma 
neustria  L . ;  Porthetria  dispar  L.;  Goniarctena  rufipes  Payk. 
Lydella  pinivor.e  Rat/.: 

Porthetria  dispar  L.: 
Meigenia  bisignata  Schin.: 

Porthetria  dispar  L.: 
Parasetigena  segregata  Rond.: 

Porthetria  dispar  L.J  7'.  monacha  L.J  Lophyrus  pini  L. 
Phryxe  erythrostoma  Hartig: 

Dendrolimus  pini  L.;  Haloicus  pinastri  L.: 


90  *    PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

Ptilotachina  larvincola  Ratz.: 

Porthetria  dispar  L.: 
Ptilotachina  monacha  Ratz.: 

Porthetria  dispar  L.: 
Tachina  larvarum  L.: 

Acronycta  rumicis  L.;  A grotis  prxcox  L.;  Arctia  caja  L.;  A.  villica  L.;  Catocola 
fraxini  L.;  Cosmotriche  potatoriah.;  Cucullia  prenanthis  B.;  Dasychira  fascellina 
L.;  Deilephila  gallii  Rott.;  D.  euphorbise  L.;  Dendrolimus  pini  L.;  Gastropacha 
quercifolia  L.;  Lasiocampa  quercus  L.;  Porthetria  dispar  L.;  P.  monacha  L.; 
Macroglossa  stellatarum  L.;  Macrothylacia  rubi  L.;  Malacosoma  castrensis  L.; 
3/.  neustria  L.;  Mamestra  brassicx  L.;  Melitxa  didyma  0.;  Melopsilus  porcel- 
lus  L.;  Ocneria  detrita  Esp.;  Olethreutes  hercyniana  Tr.;  Orgyia  ericx  Germ.; 
0.  gonostigmaF.',  Orthosia  humilis  F.;  Panolis  griseovariegata  Goeze;  Papilio 
machaon  L.;  Plusia  iota  L.;  Saturnia  pyri  Schiff.;  Stilpnotia  salicis  L.;  Vanessa 
antiopa  L.;  Vanessa  io  L.;  F.  polychloros  L.;  F.  urticse  L.;  Yponomeuta 
evonymella  L.;  Lophyrus  pini  L.;  Pamphilius  stellatus  Christ. 
Tachina  noctuarum  Rond.: 

Cosmotriche  potatoria  L.;  Porthetria  dispar  L.: 
Zenillia  libatrix  Panz.: 

Abrostola  asclepiadis  Schif 'f . ;  Brephos  nothumWo .;  Dasychira  pudibundah.;  Laren- 
tia  autumnalis  Strom.;  Porthetria  dispar  L.;  Malacosoma  neustria  L.;  Pygxra 
pigra  Hufn.;  Thaumetopcea  processionea  L.;  Yponomeuta  evonymella  L.;  I". 
padella  L. 
Zygobothria  gilva  Hartig: 

Porthetria  dispar  L.;  Stauropus  fagi  L.;  Lophyrus  laricis  Jur.;  L.  pallidus  Klug.; 
Z.  7>im  L.;  L.  rufus  Latr.;  L.  variegatus  Hartig. 
Zygobothria  bimaculata  Hartig: 

Lymantria  monacha  L.;  Lophyrus  pallidus  Klug.;  Z.  pirn  L.;  L.  rw/ws  Latr.;  L. 
socius  Klug.;  L.  variegatus  Hart.;  jC.  virens  Klug. 

Native  Diptera  Reared  from  Porthetria  dispar. 

Taehinidoe:  1 

Exorista  blanda  O.  S.  Exorista  fernaldi  Will. 

Exorista  pyste  Walk.  Tachina  mella  Walk. 

Other  than  Tachinidse:  2 

Aphiochxta  setacea  Aldr.  Phora  incisuralis  Loew 

Aphiochxta  scalaris  Loew.  Sarcophaga  sp. 

Gaurax  anchora  Loew. 


1  These  have  only  been  reared  very  occasionally  at  the  Gipsy  Moth  Parasite  Laboratory. 

2  At  the  Gipsy  Moth  Parasite  Laboratory  these  have  been  recorded  only  as  scavengers  and  not  as  para- 
sites. 


KNOWN   AND  RECORDED  PARASITES. 


91 


DIPTEROUS  PARASITES  OF  THE  BROWN-TAIL  MOTH  {Euproclis  chrysor- 

rhoea  L.). 

Foreign-  Tachimd  Parasites  of  Euproctis  chrysorrhcea. 


Recorded. 
Compsilura  concinnata  Meig. 
Echinomyia  pr.tceps  Meig. 
Erycia  ferruginea  Meig. 
Pales  pavida  Meig. 
Ttirhina  latifrotis  Rond. 
Zenillia  fauna  Meig. 
Zenillia  libatrix  Panz. 


Reared. 

Blepharidea  vulgaris  Fall. 
Compsilura  concinnata  Meig. 
Cyrh>fi>phrys  anser  Towns. 
Dexodcs  nigripes  Fall. 
Digon  ich;t  t<i  si  I  ipen  n  is  Fall . 
Digonichn  la  spinipt  nnis  Meig. 
Eudoromyia  magn  i<  om  is  Zett. 
Masirera  sylvatica  Fall. 
Xcmnrillu  sp. 
Nemorilla  notabilis  Meig. 
Pales  pavida  Meig. 
Parexorista  ehelonix  Rond. 

Tin  hum  Inn  tint  in  L. 
Tricholyya  grandis  Zctt. 

Zi  mil  hi  libntri  r  Panz. 
Zygobothria  nidicola  Towns. 

N.  B. — It  is  interesting  to  note  that  only  tlin-e  sjfecirs  art"  common  t<»  l>oth  lists. 

Recorded  Hosts  oi  Foreign  Ta<  iiimds  Reared  from  Eitroctfs  chrysorrhosa 
at  the  <  mi's  y  motm  parasite  laboratory. 

13  le  I'll  a  hi  i  >i  a  (PhTRXS)  vi  i.oaris  Fall.: 

Abraxas  grossulariutu  L.;  Adopna  lincola  ().;  A  poria  cratngi  L.;  Aruschinia  It  tana 
L.;  A.  prorsa  L.J  Argynnis  lutltonin  L.J  Antiahebe  L.;  BoOTtnia  Itiriiiurin  Dbld.; 
Bratolomia  meticulosa  L.;  Calymnia  trapczina  L.;  Cotmotricht  potatoria  L.; 

CucuUiu  aittfninidis  (in.;  (  .  astcris  Schiff.;  C  vcrbnsci  L.;  /)< ndrolimus  jn'ni  L.; 
Ephyra  lincaria  Hit.;  Epineuron  in  as  pit  is  F.;  Euclthx i  cunlu mines  L.;  Eupleria 
luciparu  111).;  Uybemia  dejol iaria  ("1.;  I/yloicus  pinnstri  I..;  HylopJiila  prasi- 
nana  L.;  Lcuamin  albipuncta  I'.;  A.  lythargyria  Esp.;  Mame&tfQ  udvena  F.; 
.1/.  persicari;i  L.;  M.  reticulata  Vill.;  Melitna  athulia  Rott.;  Mctopsilus  porccllus 
L.J  X;»  nia  typ'na  L.;  Parasemia  plantaginii  L.;  Pieris  brassies?  L.;  P.  dup/i- 
dice  L.;  /\  ra/>.T  L.;  Plu.sia  gumma  I..;  Thmnnonona  tniraria  L.;  Thaumctopn a 
pityocampa  Schiff.;  7\  processionea  L.;  Toxoeampa  pastinum  Tr.;  Vanessa 
antiopa  L.J  F.  i*o  L.;  J'.  u/7<V.»  L.;  F.  xnnthomclns  Esp.;  Zygivna  achillen 
Esp.,  db.jantkina;  Z.Jffipendui*  L.  (?);  Procrustes  coriaceus  L. 

Compsilura  concinnata  Meig.: 

See  host  list  of  tachinid  parasites  of  P,  t/ispur. 

Cyclotophrys  anser  Towns.: 

No  records  other  than  at  the  Oipsv  Moth  Parasite  Laboratory. 

Dexodes  (Lydella)  nigripes  Pall.: 

Ascomctia  ttilit/i/tosa  1 1 1  > . ;  Agrotis  candelarum  Stgr.;  Bupalus  piniarius  L.; 
Cucullia  usteris  Schiff.;  Deilephila  euphorbia  L.;  Eurrhypara  urticata  L.;  ZfeK- 
o(Aw  scutosa  Schiff.;  Hybcrnia  sp.;  Mamestra  pisi  L.J  Miana  literosa  IIw.; 
Ortho/ithti  cervinata  Schiff.;  Phragmatobia  fuliginosa  L.J  Plusia  gamma  L.; 
Porthesia  similis  Fiissl.;  Tapinostola  elymi  Tr.;  Tephroclystia  eirgaureata  Dbld.; 
Thaumetopwa  pinivora  Schiff.;  Fanessa  to  L  ;  V.  polychloros  L.J  F.  urticx  L.; 
Lophyrus  sp.;  Nematus  ribesii  Scop. 

DigonichjEta  setipennis  Fall.: 

Grapholitha  strobilclla  L.J  Notodonta  trepida  Esp.;  Pheosia  tremula  CI.  (?);  .For/i- 
cu/a  auricularia  L. 


92 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Digonich^eta  spinipennis  Meig. : 

Lasiocampa  quercus  L.;  Panolis  griseovariegata  Goeze. 

EUDOROMYIA  MAGNICORNIS  Zett.: 

Agrotis  sp.;  Hadena  adusta  Esp.;  Porthetria  dispar  L. 
Masicera  sylvatica  Fall.: 

Apopestes  spectrum  Esp.;  Cucullia  verbasci  L.;  Deilephila  euphorbise  L.;  D.  gallii 
Rott.;  D.  vespertilio  Esp.;  Dilina  tilise  L.;  Gastropacha  quercifolia  L.;  Lasio- 
campa quercus  L.;  Nonagria  typhlix  Thbg.;  Pieris  brassier  L.;  Saturnia  pav- 
onia  L.;  5.  pz/n  Schiff.;  5.  spira"  Schiff.;  Sphinx  ligustri  L. 
Nemorilla  notabilis  Meig.: 

Notoccelia  uddmanniana  L.;  Plusia  festucx  L.;  Sylepta  ruralis  Scop.;  Tachyptylia 
populella  CI. 
Pales  pavida  Meig.: 

Acronycta  tridens  Schiff.;  Agrotis  stigm'atica  Hb.;  vl.  xanihographa  F.;  Attacus 
cynthia  L.;  J.,  lunula  Fab.;  Eriogaster  catex  L.;  Emphytus  cingillum  Klug; 
Euproctis  chrysorrhoea  L.;  Orgyia  ericx  Germ.;  Panolis  griseovariegata  Goeze; 
Plusia  gamma  L.;  Thaumetopoea  processionea  L. 
Parexorista  (Exorista)  chelonle  Rond.: 

Ammoconia  csecimacula  Fab . ;  Arctia  caja  L.;  J..  Ae&e  L.;  ^4.  villicaL.;  Hadena 
secalis  L.;  Macrothylacia  rubi  L.;  Orthosia  pistacina  Fab.;  Phragmatobia  fuli- 
ginosaL.;  Rhyparia  purpurataL.;  Spilosoma  lubricipedaL.;  StilpnotiasalicisL.; 
Cimbex  femorata  L. ;  Pamphilius  stellatus  Christ. 
Tachina  larvarum  L.: 

See  host  list  of  foreign  tachinids  recorded  from  P.  dispar. 
Tricholyga  grandis  Zett.: 

Arctia  caja  L.;  Mamestra  oleracea  L.;  M.  pisi  L.;  Saturnia  pavonia  L.;  S.  pyri 
Schiff.;  Sphinx  ligustri  L.;  Thaumetopoea  pityocampa  Schiff .;  Vanessa  io  L. 
Zenillia  libatrix  Panz.: 

See  host  list  of  foreign  tachinids  recorded  as  parasites  of  P.  dispar. 
Zygobothria  nidicola  Tn.: 

No  record  other  than  at  the  Gipsy  Moth  Parasite  Laboratory. 

Recorded  Hosts  of  Foreign  Tachinids  Recorded  as  Parasitic  on  Euproctis 

chrysorrhoea. 

Compsilura  concinnata  Meig.: 

See  list  of  recorded  hosts  of  foreign  tachinids  recorded  as  parasitic  on  P.  dispar. 
Echi nomyia  pr^ceps  Meig.: 

1 /cmaris  fuciformis  L.;  Euproctis  chrysorrhoea  L 
Erycia  ferruginea  Meig.: 

Euproctis  chrysorrhoea  L.;  Melitxa  athalia  Rott.;  M.  aurinia  Rott.;  Porthesia 
similis  Fiissl.;  Vanessa  io  L. 
Pales  pavida  Meig. : 

See  list  of  recorded  hosts  of  foreign  tachinids  reared  from  E.  chrysorrhoea  L. 
Tachina  latifrons  Rond.: 

Euproctis  chrysorrhoea  L.;  Zygxna  filipendulx  L. 
Zenillia  fauna  Meig.: 

Acronycta  rumicis  L.;  Cossus  cossus  L.J  Euproctis   chrysorrhoea   L.:  Smerinthus 
ocrllatus  L. 
Zenillia  libatrix  Panz.: 

See  list  of  recorded  hosts  of  foreign  tachinids  reared  from  E.  chrysorrhoea  L. 


KNOWN  AND  RECORDED  PARASITES. 


93 


Xativf.  (American)  Tachimds  Reared  from  Euproctis  chrysorrhcea  L.,  at  the 
Gipsy  Moth  Parasite  Laboratory. 

Blepharipeza  leucophrys  Wied.  ?  Phorocera  leucanix  Coq. 

Euphorocera  elaripennis  Macq.  Sturmia  discalis  Coq. 

Erorista  griseomkans  V.  de  Wulp.  Tachina  mella  Walk. 

S.  B.— The  above  species  have  onlv  been  reared  very  occasionally.  The  species,  however,  doubt  full\ 
referred  to  Phorocera  Uucanix  Coq.  has  been  reared  through  to  the  pupal  stape  in  considerable  numbers. 
These  pup;p  have  always  been  imperfect  and  '  larviform"  and  at  the  time  of  writing  none  has  been  reared 
through  to  the  adult. 

The  compilation  of  the  catalogue  of  parasites  was  originally  under- 
taken in  the  expectation  that  it  would  prove  of  great  service  upon 
exactly  such  occasions  as  the  present,  when  the  application  of  the 
theory  of  control  by  parasites  should  be  put  to  the  test.  Its  value 
naturally  depended  upon  the  accuracy  of  the  original  records,  and  it 
was  only  right  to  suppose  that  in  the  majority  of  instances  these 
could  be  depended  upon.  It  was  equally  natural  to  suppose  that 
the  parasitic  fauna  of  such  common,  conspicuous,  and  widely  dis- 
tributed insects  as  the  gipsy  moth  and  the  brown-tail  moth  would 
be  well  represented  in  these  lists,  which  were  based  upon  a  thorough 
overhauling  of  European  literature,  and  it  was  not  expected  that  any 
parasites  of  particular  importance  would  be  found  which  were  not 
thus  recorded,  unless,  indeed,  they  were  confined  to  Continental  Asia 
or  to  Japan. 

In  the  fall  of  1*><)7.  as  soon  a^  the  turmoil  of  his  first  Bummer's 
work  permitted,  the  junior  author  attempted  to  make  use  of  the 
numerous  bibliographical  references  for  the  purpose  of  learning  as 
much  as  possible  of  the  insects  with  which  he  was  to  deal.  One 
after  another,  various  species  wore  t  aken  up,  until  he  was  in  possession 
of  practically  all  of  the  published  information  concerning  perhaps 
half  of  the  Hymenoptera  listed.  Then  he  stopped,  because  the 
information  thus  gained  was  obviously  not  worth  the  labor.  It  was 
not  so  much  that  recorded  information  was  scanty,  or  lacking  in 
interest,  but  it  was  because  in  a  great  many  instances  it  was  contra- 
dictory to  the  results  of  the  actual  rearing  work  which  had  been 
carried  on  in  the  laboratory  throughout  the  summer.  It  was  obviously 
impossible  to  accept  everything  at  its  face  value,  and  apparently 
next  to  impossible  to  choose  between  the  true  and  the  false.  But 
one  thing  remained  to  be  done,  and  that  was  to  determine  at  first 
hand  everything  which  it  was  necessary  to  know  concerning  the 
numerous  species  of  parasites  which  it  was  desired  to  introduce  into 
America. 

If  the  list  of  parasites  which  have  been  reared  at  the  laboratory 
from  imported  eggs,  caterpillars,  and  pupae  of  the  gipsy  moth  and 
the  brown-tail  moth  be  compared  with  the  lists  which  have  already 
been  given,  the  numerous  and  obvious  differences  which  are  immedi- 
ately apparent  will  serve  better  than  words  to  illustrate  the  situation 
which  confronted  us  at  the  close  of  the  season  of  1907. 


94 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


ESTABLISHMENT  AND  DISPERSION  OF  THE  NEWLY  INTRODUCED 

PARASITES. 

In  the  beginning  we  were  very  far  from  accrediting  to  that  phase 
of  the  project  which  has  to  do  with  the  establishment  and  dispersion 
of  the  newly  introduced  parasites  the  importance  which  it  deserved. 
Many  widely  diverse  species  of  insects  were  known  to  have  been 
introduced  from  the  Old  World  and  firmly  established  in  America. 
Presumably  they  were  accidentally  imported,  as  was  the  case  with 
the  gipsy  moth  and  the  brown-tail  moth;  presumably,  also,  they  had 
spread  and  increased  from  a  small  beginning,  at  first  very  gradually 
and  later  more  rapidly,  until  they  had  become  component  parts  of  the 
American  fauna  over  a  wide  territory.  The  circumstances  under 
which  the  gipsy  moth  was  imported  were  well  known,  and  a  good 
guess  had  been  made  as  to  those  which  resulted  in  the  introduction 
of  the  brown-tail  moth.  But  these  were  and  are  rare  exceptions  in 
this  respect,  and  for  the  most  part  the  preliminary  chapters  in  the 
story  of  each  of  the  insect  immigrants  never  have  been  and  probably 
never  will  be  written. 

Because  the  two  very  conspicuous  instances  of  the  gipsy  moth  and 
the  brown-tail  moth  were  constantly  and  automatically  recurring 
whenever  the  probable  future  of  the  intentionally  introduced  para- 
sites was  considered,  it  was,  perhaps,  taken  a  little  too  much  for 
granted,  that  they  were  to  be  considered  as  typical  and  significant 
of  what  to  expect.  In  each  instance  the  invasion  started  from  a 
small  beginning,  and  while  the  subsequent  histories  were  different, 
the  more  rapid  spread  of  the  brown-tail  moth  was  directly  due  to  the 
fact  that  the  females  were  capable  of  flight,  and  the  relatively  slow 
advance  of  the  gipsy  moth  into  new  territory  to  the  reverse.  Even 
the  brown-tail  moth  was  for  some  years  confined  to  a  comparatively 
limited  area,  and  it  was  rather  expected  that  the  parasites,  if  they 
established  themselves  at  all,  would  remain  for  a  similar  period  in  the 
immediate  vicinity  of  the  localities  where  they  were  first  given  their 
freedom. 

Accordingly,  in  accepting  this  theory  without  submitting  it  to  a 
test,  attempts  were  made  to  encompass  the  rapid  dissemination  of  the 
parasites  coincidently  with  their  introduction.  In  1906  and  1907 
the  parasites  which  were  reared  from  the  imported  material  were 
most  ly  liberated  in  small  and  scattered  colonies.  In  a  few  instances 
this  procedure  was  the  best  which  could  have  been  adopted;  in  others 
the  worst.  Small  colonies  of  Calosoma,  for  example,  remained  for 
several  years  in  the  immediate  vicinity  of  the  point  where  the  parent 
beetles  were  first  liberated  before  any  material  dispersion  was  appar- 
ent (see  PI.  XXIV),  and  the  small  colony  was  thus  justified. 
The  gipsy-moth  egg  parasite  Anastatus,  as  was  later  determined, 


ESTABLISHMENT  AND  DISPERSION. 


95 


spreads  at  a  rate  of  but  a  few  hundred  feet  per  year,  and  if  it  is  to 
become  generally  distributed  throughout  the  gipsy-moth-infested 
area  within  a  reasonable  time,  natural  dispersion  must  be  assisted  by 
artificial. 

These,  however,  are  both  exceptions.  In  the  case  of  Monodonto- 
merus,  and  perhaps  of  other  parasites,  gregarious  in  their  habit,  it  is 
not  only  conceivable  but  probable  thai  a  single  fertilized  female 
would  be  sufficient  to  establish  the  species  in  a  new  country,  because 
the  union  between  the  sexes  is  effected  within  the  body  of  the  host 
in  which  they  were  reared.  No  matter  how  far  a  female  may  range 
and  no  matter  how  widely  separated  the  victims  of  her  maternal 
Instincts,  her  progeny  will  rarely  die  without  each  finding  it>  mate. 
Species  having  such  habits  are  eminently  well  fitted  to  establish 
themselves  wherever  they  secure  foothold,  even  in  the  smallest 
numbers,  and  the  small  colony  is  again  justified. 

Many  of  the  hymenopterous  parasites,  and  very  likely  all  of  them, 
are  capable  of  parthenogenetic  reproduction,  and  here  again  is  a  factor 
which  becomes  of  considerable  importance  in  this  connection.  vSome 
few  of  these  are  thelyotokous  (bearing  females  only)  and  as  such  are 
eminently  well  fitted  to  establishment  in  a  new  country  under  other- 
wise unsatisfactory  conditions.  Most  are  arrhenotokous  (bearing 
males  only),  and  such  are  probably  better  fitted  to  establishment 
than  would  he  the  case  if  the  species  were  wholly  incapable  of  par- 
thenogenetic reproduction.  It  has  been  proved,  for  example,  that 
a  single  female  of  a  strictly  arrhenotokous  species,  may,  through 
fertilization  by  her  own  part  henogenet  ically  produced  offspring, 
become  the  progenetrix  of  a  race  the  vigor  of  which  appears  not  to 
be  immediately  affected  by  the  fact  that  their  continued  multiplica- 
tion must  be  considered  as  the  closest  form  of  inbreeding. 

Whenever  opportunity  has  offered  the  ability  of  the  various 
species  to  reproduce  pathenogenetically  has  been  studied,  and  many 
interesting  and  some  peculiar  facts  have  been  discovered  which,  it  is 
hoped,  will  serve  as  the  subject  for  a  technical  paper  later  on.  This 
power  appears  to  be  confined  to  the  Hymenoptera,  however,  and  the 
tachinid  parasites,  like  their  hosts,  are  rarely  or  perhaps  never 
parthenogenetic. 

When  continued  existence  of  an  insect  in  a  new  country  is  de- 
pendent upon  the  mating  of  isolated  females  it  is  at  once  evident 
that  it  is  also  dependent  upon  the  rapidity  of  dispersion  and  upon  the 
number  of  individuals  which  are  comprised  in  the  original  colony. 
One  of  the  most  constant  sources  of  surprise  is  in  the  rapidity  with 
which  the  parasites  disperse.  One,  Monodontomerus,  has  undoubt- 
edly extended  its  range  for  more  than  200  miles  in  the  course  of  the 
five  years  which  have  elapsed  since  its  liberation,  and  there  is  no 


96 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


reason  to  believe  that  others  among  the  introduced  species  will  not 
disperse  at  an  equal  rate,  once  they  are  sufficiently  well  established. 

But  Monodontomerus  is  eminently  well  fitted  for  dispersion,  and 
its  case  is  altogether  different  from  that  of  a  tachinid  which  is  de- 
pendent upon  sexual  reproduction  for  the  continuation  of  the  spe- 
cies. A  few  hundred  individuals,  spreading  rapidly  toward  all 
points  of  the  compass,  soon  become  widely  scattered,  and  it  is,  and 
will  remain  for  a  long  time,  a  question  just  how  rare  an  insect  may 
be  and  each  individual  still  be  able  to  find  its  mate.  That  the  indi- 
viduals of  the  first  colonies  of  many  of  the  tachinid  parasites  scat- 
tered so  widely  as  to  make  the  mating  of  the  next  generation  purely 
a  matter  of  chance  and  of  rare  occurrence  is  now  accepted  as  well 
within  the  bounds  of  probability. 

The  first  serious  doubts  as  to  the  wisdom  of  the  policy  of  the  small 
colony  were  felt  in  1907,  and  beginning  with  June  of  that  year  larger 
colonies  were  planted  in  the  instance  of  every  species  than  had  been 
the  practice  up  to  that  time.  In  the  fall  of  1908  the  recovery  of 
Monodontomerus  over  a  wide  territory  lent  strength  to  these  half- 
formed  convictions,  and  when,  during  1909  and  1910,  one  after 
another  of  the  various  parasites  were  recovered  under  circumstances 
which  were  in  most  cases  essentially  similar,  all  doubts  vanished  as 
to  the  wisdom  of  the  course  finally  adopted.  At  the  present  time 
there  is  no  more  inexorable  rule  governing  the  conduct  of  the  labora- 
tory than  that  establishment  of  a  newly  introduced  parasite  is  first 
to  be  secured,  while  dispersion,  if  later  developments  prove  that  it 
can  be  artificially  aided,  comes  as  a  wholly  secondary  consideration. 
For  the  most  part,  however,  dispersion  may  be  left  to  take  care  of 
itself. 

An  even  larger  appreciation  of  the  necessity  for  strong  colonies 
has  been  reached  during  the  present  winter  (1910-11),  coincidently 
with  the  results  of  the  scouting  work  for  Monodontomerus  and 
Pteromalus  in  the  brown-tail  moth  hibernating  nests.  (See  maps, 
Pis.  XXII,  XXV.)  The  details  will  not  be  given  in  this  imme- 
diate connection,  but  they  will  be  found  later  on  in  connection 
with  the  discussion  of  these  species.  It  is  sufficient  at  this  time  to 
say  that  the  circumstances  under  which  the  Pteromalus  was  recov- 
ered after  the  lapse  of  two  years  following  its  colonization  were  such 
as  to  cast  doubts  upon  the  conclusions  which  had  been  tentatively 
reached  concerning  the  inability  of  certain  other  species  to  exist  in 
America,  and  their  possible  significance  had  something  to  do  with 
the  decision  to  continue  the  work  of  parasite  importation  along 
wholly  different  lines  in  1911.  It  may  be,  after  all,  that  40,000 
individuals  of  Apanteles  fulviyes  are  not  enough  to  make  one  good 
colony.  - 


DISEASE  IX  CONTROL  OF  MOTHS. 


97 


DISEASE  AS  A  FACTOR  IN  THE  NATURAL  CONTROL  OF  THE  GIPSY 
MOTH  AND  THE  BROWN-TAIL  MOTH. 

In  continuing  this  work  consideration  must  be  given  to  the  proba- 
ble effect  which  the  prevalence  of  disease  would  possibly  have  in  the 
reduction  of  the  gipsy  moth  and  the  brown-tail  moth  to  the  ranks 
of  ordinary  rather  than  of  extraordinary  pests.  In  America,  as  is 
generally  well  known,  the  brown-tail  moth  is  annually  destroyed  to 
an  extraordinary  extent  as  the  result  of  an  epidemic  and  specific 
fungous  disease,  while  the  gipsy  moth  is  frequently  subjected  to  very 
material  diminution  of  numbers  through  a  much  less  well  known 
affection  popularly  known  as  "the  wilt,"  apparently  similar  to  the 
silkworm  disease  "flacherie." 

In  more  respects  than  one  the  prevalence  of  these  diseases  has 
been  inimical  to  the  prosecution  of  the  parasite  work.  In  the  be- 
ginning, when  it  was  expected  that  the  parasites  would  remain  in 
the  immediate  vicinity  of  the  localities  where  they  were  first  given 
their  freedom,  great  pains  were  taken  to  provide  colony  sites  in 
situations  where  the  caterpillars  were  not  only  common  but  where 
there  was  reason  to  believe  that  they  would  remain  healthy  for  at 
least  one  or  two  years.  This  was  an  exceedingly  difficult  matter, 
and  one  which  Was  the  cause  of  more  troubles,  doubts,  and  fears 
during  1(.)()7  and  luOS  than  almost  any  other  phase  of  the  parasite 
work. 

With  the  final  recognition  of  the  great  superiority  of  the  large  col- 
ony, which  came  about  through  a  better  knowledge  of  the  powers  of 

rapid  dispersion  possessed  by  the  parasites,  this  seeming  obstacle  to 
success  wholly  disappeared,  except  in  the  case  of  such  parasites  as 

AnaM  at  us,  which  actually  did  remain  in  the  spot  where  they  were 
placed,  and  which  could  not  travel  beyond  a  certain  limited  radius, 
no  matter  how  great  the  Qecessity. 

At  the  present  time  the  association  with  the  parasite  problem  of 
the  otherwise  wholly  separate  question  of  disease  as  a  factor  in 
the  control  of  the  gipsy  moth  and  the  brown-tail  moth  is  entirely 
(•online, 1  to  speculations  as  to  the  probable  future  of  these  pests,  pro- 
vided their  control  is  left  to  disease  alone.  If.  as  is  conceivable, 
effective  control  is  exerted  through  disease,  further  importation  of 
parasites  is  rendered  not  only  needless  but  wholly  undesirable.  If, 
on  the  contrary,  such  control  is  likely  to  be  inefficient,  from  an  eco- 
nomic standpoint,  every  effort  should  be  exerted  to  make  the  parasite 
work  a  success.  In  other  words,  the  decision  as  to  the  adoption  of  a 
policy  for  the  future  conduct  of  the  activities  of  the  laboratory 
depended  very  largely  upon  whether  or  not  disease  seemed  likely  to 
become  effective  in  the  case  of  the  more  important  of  the  two  pests. 
The  fact  that  the  present  plans  provide  for  the  continuation  of  the 
95677°— Bull.  91—11  7 


98  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

work  along  even  more  energetic  lines  than  in  the  past  indicates  suffi- 
ciently well  the  character  of  the  decision  finally  reached. 

This  is  not  the  place  for,  nor  are  the  writers  prepared  to  enter 
into,  a  discussion  of  the  caterpillar  diseases  of  the  gipsy  moth  and 
the  brown-tail  moth,  but  it  is  perhaps  not  out  of  place  to  recount 
some  of  the  incidents  which  have  been  taken  into  consideration  in 
the  present  instance.  In  this,  as  in  many  others  similar  in  character, 
the  brown-tail  moth  has  largely  been  ignored,  owing  to  its  being 
generally  considered  as  the  lesser  pest  of  the  two.  As  frequently 
before,  the  work  upon  the  brown-tail  moth  parasites,  although 
pursued  quite  as  actively  as  that  upon  the  parasites  of  the  gipsy 
moth,  was  relegated  to  a  secondary  position. 

Very  little  has  been  published  concerning  the  gipsy-moth  cater- 
pillar disease  previously  to  1907,  when  the  junior  author  first  had 
opportunity  to  familiarize  himself  with  the  situation  at  first  hand. 
It  was  to  him  a  novelty  when,  early  in  the  summer  of  that  year, 
wholesale  destruction  of  the  half-grown  caterpillars  was  first  noticed 
in  numerous  localities  before  they  had  succeeded  in  effecting  the  com- 
plete defoliation  of  the  trees  and  shrubs  upon  which  they  were  feeding. 
In  all  its  essential  characters  the  disease  was  similar  to  that  which 
had  swept  over  the  army  of  tent  caterpillars  which  were  defoliating 
the  apple  and  cherry  trees  in  southern  New  Hampshire  in  1898, 
as  recounted  in  the  bulletin  upon  the  parasites  of  that  insect,  pub- 
lished as  No.  5  in  the  Technical  Series  of  the  New  Hampshire  Agri- 
cultural Experiment  Station.  It  was  believed  of  this  disease,  at 
the  time  when  these  investigations  were  being  conducted,  that  it 
was  infectious,  since  the  inhabitants  of  whole  nests  would  all  perish 
simultaneously.  At  the  same  time,  its  infectious  or  contagious 
nature  was  not  established. 

On  the  supposition  that  the  disease  of  the  tent  caterpillar  was 
infectious,  and  that  that  of  the  gipsy-moth  caterpillars  was  similar 
in  character,  it  looked  for  a  time  as  though  the  parasite  work  was 
destined  to  an  untimely  end  through  the  destruction  of  the  gipsy- 
moth  caterpillars  before  the  parasites  had  opportunity  to  establish 
themselves  and  increase  to  the  point  of  efficacy.  Neither  was 
there  anything  observed  during  the  summer  of  1907  to  render  this 
supposition  untenable,  except  (and  from  an  economic  standpoint  the 
exception  was  one  of  grave  importance)  the  fact  that,  taking  the 
infested  area  as  a  whole,  there  was  a  tremendous  increase  in  the 
number  of  egg  masses  of  the  gipsy  moth  in  the  fall  of  1907  over  the 
number  which  had  been  present  the  previous  spring. 

There  did  not  seem  to  be  any  particular  reason  why  the  disease 
should  not  increase  in  effectiveness  as  time  passed  on,  however,  and 
when  in  the  spring  of  L908  myriads  of  caterpillars  in  the  first  stage- 
were  found  "wilting"  in  the  forests  in  .Melrose,  and  when  just  a  little 


DISEASE  IS  CONTROL  OF  MOTHS. 


99 


later  practically  every  caterpillar  was  destroyed  in  one  particular 
locality  which  had  been  selected  as  a  good  place  for  the  very  first 
colony  of  Apantdes  fulript  s,  there  seemed  to  be  reason  to  hope  for 
speedy  relief  through  disease.  About  this  time  these  hopes  were 
rudely  shattered  by  the  failure  of  several  attempts  to  demonstrate 
the  infectious  or  contagious  nature  of  the  disease  through  experi- 
ments carried  on  at  the  laboratory.  Its  noncontagious  nature  was 
further  indicated  by  the  facl  that  it  did  aol  spread  across  a  narrow 
roadway  near  the  laboratory,  one  side  of  which  was  swarming  with 
dying  caterpillars,  while  the  other  was  peopled  with  an  alarming 
but  not  destructive  abundance  of  healthy  ones.  It  appeared,  after 
all,  as  though  the  views  often  expressed  by  Mr.  A.  H.  Kirkland  (at 
that  time  superintendent  of  the  moth  work  in  Massachusetts)  to  the 
effect  that  the  disease  was  nothing  more  thai)  the  natural  concomi- 
tant of  overpopulation,  and  that  an  insufficient  or  unsuitable  food 
supply  was  the  true  explanation  of  its  prevalence,  were  right.  That 
it  was  not  to  be  depended  upon  for  immediate  results  was  certain 
when,  at  tiie  close  of  190S,  a  further  alarming  and  apparently  an 
unaffected  increase  in  the  distribution  and  abundance  of  the  gipsy 

moth  in  Massachusetts  and  New  Hampshire  was  found  to  have  taken 
place  wherever  conditions  were  not  such  as  to  render  destruction 
through  disease  the  only  thing  which  saved  the  gipsy  moth  from 
extinction  through  starvation,  or  where  active  hand  suppression  work 
had  not  been  undertaken. 

In  1909,  and  again  in  1910,  observations  upon  the  progress  of  the 
disease  were  made  almost  daily  throughout  the  caterpillar  season. 
It  was  no  longer  looked  upon  as  a  serious  obstacle  to  the  success  of 
the  parasite  work,  except  as  it  interfered  (as  it  Frequently  did  most 
seriously)  with  the  work  of  colonizing  Anastatus,  and  to  a  lesser 
extent  Calosoma.  It  was  also,  as  ever,  the  cause  of  serious  trouble 
whenever  attempts  were  made  to  feed  caterpillars  in  the  laboratory 
in  confinement . 

The  disease  acquired  new  interest,  however,  through  the  gradual 
accumulation  of  evidence  tending  to  support  the  theory  that  it  was 
either  transmissible  from  one  generation  to  another  through  the  egg 
or  that  a  tendency  to  contract  it  was  thus  transmitted. 

Recognition  of  tins  characteristic  through  cumulative  evidence 
resulting  from  more  occasional  or  specific  observations  than  it  would 
be  possible  to  review  at  tliis  time,  was  accompanied  by  the  almost 
equally  apparent  fact  that  the  disease  was  becoming  slightly  more 
effective  at  a  somewhat  earlier  stage  in  the  progress  of  a  colony  of 
the  gipsy  moth  following  its  establishment  in  a  new  locality.  It 
was  found,  for  example,  in  New  Hampshire  in  colonies  which  had 
barely  reached  the  stripping  stage.  A  few  years  before  the  cater- 
pillars composing  such  colonies  would  naturally  have  migrated  from 


100 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


the  stripped  trees  to  others  in  the  vicinity,  and  it  is  an  unmistakable 
fact  that  such  migrations,  which  have  several  times  been  mentioned 
in  the  earlier  reports  of  the  State  superintendent  of  moth  work,  are 
now  decidedly  less  frequent,  even  without  taking  into  consideration 
the  greater  territory  throughout  which  the  moth  is  now  present  in 
destructive  abundance.  Although  the  junior  author  has  personally 
visited  large  numbers  of  outlying  colonies  of  the  moth  in  the  course 
of  1908,  1909,  and  1910,  he  has  yet  to  see  one  in  which  the  disease 
had  not  appeared  coincidently  with  the  development  of  the  colony 
to  the  stripping  stage,  if  not  slightly  in  advance  of  that  time. 

It  is  probably  safe  to  say  that  such  conditions  as  are  described  in 
the  first  annual  report  of  the  superintendent  of  moth  work  as  pre- 
vailing over  a  large  territory  in  the  old  infested  section  during  1904 
and  1905,  will  probably  not  immediately  recur  in  the  history  of  the 
gipsy  moth  in  eastern  Massachusetts.  That  something  approaching 
this  may  result  in  parts  of  New  Hampshire  is  well  within  the  bounds 
of  probability,  and  that  the  conditions  will  be  very  bad  in  that  State 
during  the  course  of  the  next  few  years  as  well  as  in  some  of  the 
towns  in  Massachusetts  may  be  accepted  as  most  probable.  What- 
ever may  be  the  condition  presented  by  the  older  infested  sections 
in  eastern  Massachusetts  five  or  ten  years  from  now,  the  only  hope 
of  preventing  an  ever-increasing  wave  of  destruction  from  spreading 
over  western  Massachusetts,  across  New  Hampshire  and  Vermont, 
and  over  the  border  into  the  State  of  New  York,  seems  to  lie,  as 
always,  in  an  increasing  expenditure  for  hand  suppression  or  in  the 
success  of  the  experiment  in  parasite  introduction.  Through  the 
methods  now  in  operation  it  is  probable  that  the  pest  will  very  largely 
be  prevented  from  making  long  "  jumps,"  which  would  otherwise 
have  been  of  frequent  occurrence,  but  the  slower  and  more  steady 
natural  spread,  through  the  agency  of  wind,  and  probably,  when  the 
headwaters  of  the  Connecticut,  Hudson,  and  Ohio  are  reached,  by 
water,  must  be  considered  in  every  attempt  to  discount  the  future. 
It  was  taken  into  consideration  when  the  future  of  the  parasite  work 
was  decided  upon. 

In  the  course  of  the  studies  of  the  parasites  and  parasitism  of  native 
insects  which  have  been  undertaken  in  connection  with  those  of  the  para- 
si  tes  of  the  gipsy  moth  and  the  brown-tail  moth,  no  less  than  three  spe- 
cies have  been  encountered  which  are  controlled  to  some  extent  by  a 
disease  which  bears  a  very  close  superficial  resemblance  to  the  "wilt" 
of  the  gipsy  moth.  These  are  the  white-marked  tussock  moth,  the 
tent  caterpillar,  and  the  "pine  tussock  moth." 

The  white-marked  tussock  moth  (Hemerocampa  leucostigma  S.  &  A.) 
is  well  known  as  a  defoliating  pest  in  cities,  and  has  been  so  abundant 
as  at  times  to  become  a  rival  of  the  gipsy  moth  in  its  destructive 
capacities  in  certain  of  the  larger  cities  in  southeastern  New  England. 


DISEASE  IN  CONTROL  OF  MOTHS. 


101 


It  is  very  subject  to  a  "  wilt  "  disease,  and  qo  colony  has  been  observed 
which  has  reached  such  proportions  as  to  threaten  the  defoliation  of 
street  trees  in  which  the  disease  has  not  appeared.  In  one  instance 
the  disease  was  so  prevalent  as  to  destroy  practically  all  of  the  cater- 
pillars, and. a-  in  the  case  of  the  gipsy  moth,  the  scattering  caterpillars 
which  hatched  from  the  eggs  deposited  by  the  few  survivors  were 
seriously  affected  the  following  year,  notwithstanding  the  presence  of 
an  abundance  of  food.  Furthermore,  caterpillars  hatching  from 
eggs  collected  in  this  and  similar  colonies  removed  to  the  country 
where  the  few  native  caterpillars  to  be  found  have  always  been  remark- 
ably healthy,  perished  t  hrough  the  "  wilt  "  exact  ly  as  though  t  hey  had 
hatched  in  the  city. 

Nevertheless,  the  white-marked  tussock  moth  has  been  for  long,  is 
now,  and  probably  will  remain  the  worst  defoliating  insect  enemy  of 
such  trees  as  the  horse  chestnut .  maple, sycamore, etc..  in  si  rictly  urban 
communities  in  the  Eastern  States  generally.  It  does  not  appear  un- 
reasonable to  suppose  that  the  gipsy  moth  may  similarly  cont  inue  to  be 
a  pest  in  spite  of  the  disease.  As  a  matter  of  fact,  every  observation 
which  has  been  made  upon  either  the  fungous  disease  of  the  brown- 
tail  moth  caterpillars,  the  wilt  disease  of  the  gipsy-moth  caterpillars, 
or  diseases  of  other  de folia t  ing  caterpillars,  such  as  that  of  t  he  white- 
marked  t  ussock  moth,  the  tent  caterpillar,  and  the  "  pine  t  ussock  mot  h," 
has  tended  to  confirm  t he  conclusion  that  BUch  insect  epidemics  rarely 
play  more  than  the  one  role  in  the  economy  of  nature.  They  do  not 
])nr<nt  an  insect  from  increasing  to  an  extent  which  renders  it  a  pest, 
but  they  may,  and  frequently  do.  i-ender  very  eflicient  service  in  effect- 
ing a  wholesale  red  net  ion  in  t  he  abundance  of  such  insects  when  other 
agencies  fail.  When  the  inject  in  question  is  ordinarily  controlled 
by  parasites,  as  appears  t<>  he  the  case  with  the  white-marked 

tUSSOck  QOLOth,  the  "pine  tUSSOck  moth,"  etc.,  it  i>  probable  that  a 
long  time  will  elapse  before  it  will  again  encounter  the  combination  of 
favorable  circumstances  which  make  possible  abnormal  increase. 

When, as  with  the  white-marked  t  ussock  mot  li  in  cit  ic^.  i  Ik-  tent  cat- 
erpillar in  southeastern  New  England, or  t  he  brown-f  ail  moth  am!  gipsy 
moth  in  America,  adequate  control  by  parasites  i^  lacking,  reduction 
in  numbers  through  disease  is  not  likely  to  result  in  more  than  tem- 
porary relief.  The  more  complete  the  destruction  wrought  by  the 
insect  the  longer  the  period  which  must  necessarily  elapse  before  it 
again  reaches  the  state  of  destructive  abundance  and,  looking  at  it 
from  this  standpoint,  it  is  not  unlikely  that  the  gipsy  moth  is  much 
more  abundant  at  the  present  time  than  it  would  have  been  had  it 
not  been  for  the  prevalence  of  disease.  There  are,  each  year,  an 
abundance  of  localities  where  the  destruction  of  a  great  majority  of 
the  caterpillars  by  disease  has  been  the  only  thing  which  has  saved  the 
whole  race  from  complete  extinction  in  that  locality  through  con- 


102  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

sumption  of  the  entire  supply  of  available  food  before  growth  was 
completed.  Under  such  circumstances  the  disease  has  been  of  posi- 
tive benefit  to  the  gipsy  moth,  rather  than  the  reverse. 

STUDIES  IN  THE  PARASITISM  OF  NATIVE  INSECTS. 

Among  a  considerable  number  and  variety  of  native  insects  studied 
at  the  laboratory  which  resemble  the  gipsy  moth  in  habit,  or  which 
are  more  or  less  closely  allied  to  it  in  their  natural  affinities,  no  two 
have  been  found  in  the  economy  of  which  parasitism  has  played  an 
exactly  similar  role.  There  is  this  to  be  said,  however,  that  only  one 
amongst  them,  and  this  the  tent  caterpillar,  appears  to  be  ineffectually 
controlled  by  parasitism,  except  under  unusual  circumstances. 

Several  very  beautiful  examples  of  control  by  parasites  have  been 
encountered  in  the  course  of  these  investigations,  and,  comparatively 
speaking,  the  exceptional  instances  in  which  parasites  lose  control 
through  one  reason  or  another  are  exceedingly  rare.  Such  instances 
are  usually,  if  not  inevitably,  accompanied  by  a  conspicuous  outbreak 
of  the  insect  in  question. 

The  destructiveness  of  the  white-marked  tussock  moth  in  cities  is 
apparently  due  to  the  fact  that  it  is  peculiarly  adapted  to  life  under 
an  urban  environment.  It  is  an  arboreal  insect,  and  one  which  is  pre- 
vented through  the  winglessness  of  its  females  from  dispersing  over 
the  country  as  the  brown-tail  moth,  for  example,  would  do  under  simi- 
lar circumstances.  Its  parasites,  on  the  other  hand,  are  not  always 
fitted  for  a  peculiarly  arboreal  existence.  Many  of  them  are  partially 
terrestrial,  and  in  addition  they  are  strong  upon  the  wing. 

Most  of  the  introduced  parasites  of  the  gipsy  moth  and  brown-tail 
moth  which  are  known  to  have  established  themselves  in  America  are 
known  to  be  dispersing  at  a  rapid  rate.  Several  of  them  have  been 
reared  as  parasites  of  the  white-marked  tussock  moth  from  cater- 
pillars or  pupae  collected  under  urban  surroundings,  and  since  we 
have  positive  proof  of  their  wandering  habits  there  is  every  reason  to 
behove  that  the  native  parasites  of  the  tussock  moth  possess  similar 
characteristics.  That  is  to  say,  instead  of  staying  within  the  limited 
area  in  which  their  host  abounds,  they  are  likely  to  scatter  throughout 
the  country  immediately  following  the  completion  of  their  transforma- 
tions. They  are  neither  fitted  for  continued  existence  in  the  city  to 
the  degree  which  is  characteristic  of  their  host,  nor  are  they  compelled, 
like  it,  to  accept  it  when  they  find  themselves  city-born  through 
chance  ancestral  wanderings. 

Every  season's  observations  (and  for  four  consecutive  years  the 
tussock  moth  has  received  more  than  a  modicum  of  attention)  has 
added  arguments  to  support  the  contention  that  the  white-marked 
tussock  moth  is  controlled  in  the  country  through  parasitism  and  not 
by  birds  or  other  predators.    In  any  event  it  is  controlled  to  such  an 


PARASITISM  OF  NATIVE  INSECTS. 


103 


extent  as  to  have  made  a  study  in  parasitism  under  strictly  rural  con- 
ditions very  difficult,  except  when  eggs  or  caterpillars  have  been  arti- 
ficially colonized  for  the  purpose. 

The  outbreak  of  the  Ileterocampa  in  New  Hampshire  and  Maine  is 
another  exceptional  instance.  In  many  respects  the  results  of  the 
relatively  limited  study  given  to  this  insect  were  the  most  remarkable 
of  any,  since  there  was  offered  what,  to  the  writers,  was  the  unique 
spectacle  of  unrestricted  increase  being  checked  through  starvation 
without  the  intervention  of  disease.  Notwithstanding  the  fact  that 
the  abundance  of  this  insect  was  so  great  as  to  bring  about  complete 
defoliation  of  its  favored  trees  over  a  very  wide  area,  not  a  sign  of  dis- 
ease was  observed  in  the  fall  of  1909  in  forests  where  millions  of  cater- 
pillars were  literally  starving  to  death.  The  final,  thoroughly  effect- 
ive, and  miraculously  complete  subjugation  of  the  outbreak,  which 
resulted  in  the  insect  dropping  from  the  abundance  above  mentioned 
to  what  is  perhaps  less  than  its  normal  numbers  in  the  course  of  a 
single  year,  has  already  been  described  in  a  paper  which  appeared  in  a 
recent  number  of  the  Journal  of  Economic  Entomology.  There  is 
every  reason  to  believe  that  it  W"as  entirely  t  he  result  of  insect  enemies, 
including  both  parasites  and  a  predaceous  beetle,  which  latter, 
through  its  ability  to  increase  abnormally  at  the  direct  expense  of 
that  particular  insect ,  played  a  role  exactly  comparable  to  that  of  the 
true  facultative4  parasites.  Such  another  outbreak  of  Ileterocampa 
has  never  been  known,  and  it  is  probable  that  it  will  be  very  many 
years  before  a  combination  of  conditions  makes  its  repetition  possible. 
It  is  altogether  probable  that  dining  this  period  the  parasites  will 
remain  in  full  COnl  rol. 

A  third  exceptional  instance  is  the  present  outbreak  of  the  "pine 
tussock  moth"  in  Wisconsin.  This  interesting  and.  as  it  has  proved 
itself,  potentially  destructive  insect  is  decidedly  rare  in  Massachusetts, 
but  notwithstanding  its  scarcity  a  sufficient  number  was  collected 
in  1908  and  1909  to  make  possible  a  study  of  its  parasites.  Para- 
sitism to  an  extent  rarely  exceeded  amongst  leaf-feeding  Lepidoptera 
was  found  to  be  existent,  and  it  is  safe  to  say  that  had  it  not  been  for 
its  parasites  the  host  would  have  increased  at  least  fivefold  or  six- 
fold in  1909 over  the  numbers  which  were  present  in  1908.  Such  a 
rate  of  increase,  if  continued,  would  have  placed  it  among  the  ranks 
of  destructive  insects  in  a  very  few  years,  and  it  appears  that  some- 
thing of  this  soil  actually  occurred  in  northern  Wisconsin.  There, 
some  years  ago,  it  reached  a  stage  of  abundance  which  resulted  in 
partial  or  complete  defoliation  of  pine  throughout  a  considerable 
territory  and,  as  was  expected,  a  relatively  small  percentage  of  the 
caterpillars  and  pupae  were  found  to  be  parasitized.  Existing  para- 
sitism in  1910  was  not  sufficiently  effective  to  prevent  its  increase 
to  a  point  which  would  have  made  complete  defoliation  of  its  food 


104  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

plant,  and  consequently  its  death  through  starvation,  an  accomplished 
fact  had  its  abundance  not  been  reduced  through  the  prevalence  of  a 
disease  superficially  similar  to  the  "wilt"  of  the  gipsy  moth. 

The  fall  webworm  is  generally  a  common  and  abundant  insect  in 
New  England j  but  rarely  as  common  or  abundant  as  it  frequently 
becomes  in  the  South.  An  elaborate  study  of  its  parasites  and  the 
effect  which  parasitism  apparently  played  in  effecting  its  control  was 
made  in  the  fall  of  1910,  with  interesting  results.  It  was  found  that 
the  prevailing  percentage  of  parasitism  was  sufficient  to  offset  an 
increase  of  no  less  than  fourfold  annually,  and  even  at  that  there  is 
reason  to  believe  that  our  results  err  on  the  side  of  conservatism. 
The  elimination  of  these  parasites  for  a  very  short  period  of  years 
would  undoubtedly  be  followed  by  an  increase  of  the  host  comparable 
to  that  of  the  gipsy  moth. 

The  one  insect  studied  at  the  laboratory  which  appears  habitually 
and  under  its  normal  environment  to  become  so  unduly  abundant 
as  to  invite  destruction  through  disease  at  regular  intervals  is  the 
tent  caterpillar. 

In  the  report  upon  its  parasites,1  it  was  contended  that  they  played 
a  part  subservient  to  that  taken  by  the  disease,  and  this  statement 
drew  forth  some  criticism  at  the  time  of  its  publication.  It  is  a 
satisfaction  to  note  that  the  original  contention  appears  to  be  upheld 
by  the  results  of  studies  conducted  at  the  gipsy-moth  parasite  labora- 
tory. These  results  seem  to  justify  the  further  contention  that  the 
present  status  of  the  tent  caterpillar  is,  in  a  way,  prophetic  of  that 
which  would  result  were  the  gipsy  moth  to  be  left  to  the  control 
of  its  disease. 

At  frequent  but  irregular  intervals  the  tent  caterpillar  increases 
to  such  an  extent  as  to  become  a  pest,  and  unless  artificially  checked 
it  defoliates  fruit  trees  in  southern  New  England.  That  it  never 
reaches  the  destructiveness  characteristic  of  the  gipsy-moth  invasion 
is  seemingly  due  to  difference  in  habit.  As  is  well  known,  the  gipsy- 
moth  caterpillar  is  almost  an  omnivorous  feeder  and  the  female  moth 
is  incapable  of  flight.  Its  eggs  are  deposited  indiscriminately  in 
every  conceivable  place  to  which  a  caterpillar  or  moth  can  gain 
access.  The  adult  of  the  tent  caterpillar  is  in  no  way  restricted  to 
the  immediate  vicinity  of  the  locality  where  it  chose  to  pupate  as  a 
caterpillar,  but,  instead,  uses  what  really  amounts  to  an  unwise 
amount  of  discretion  in  its  selection  of  a  place  for  oviposition. 
Cherry  first  and  then  apple  is  selected  in  preference  to  all  other  food 
plants,  and  with  the  exception  of  a  limited  number  of  other  rosaceous 
trees  and  shrubs,  its  eggs  are  almost  never  found  elsewhere.  As  a 
result,  when  it  is  at  nil  abundant  its  caterpillars,  which  have  not  the 

1  Technical  Bulletin  5,  New  Hampshire  Agricultural  Experiment  Station. 


PARASITISM  IN  INSECT  CONTROL. 


105 


wandering  characteristics  of  those  of  the  gipsy  moth,  but  rather  the 
opposite,  find  themselves  crowded  in  excessive  numbers  upon  a 
limited  variety  of  shrubs  and  trees;  complete  defoliation  of  these 
comparatively  few  host  plants  quickly  follows,  and  weather  condi- 
tions being  favorable  to  the  development  of  disease,  wholesale 
destruction  is  all  that  intervenes  between  an  unnatural  migration  or 
starvation.  Such  reduction  is  followed  by  a  period  of  years  during 
which  the  parasites  check  but  do  not  overcome  the  tendency  to 
increase,  and  it  is  only  a  little  while  before  the  process  is  repeated. 

There  were,  in  certain  localities  in  eastern  Massachusetts  in  the 
summer  of  1910,  cont  inuous  strips  of  roadside  grown  up  to  a  variety  of 
trees  and  shrubs,  the  most  of  which  were  defoliated  by  tent  cater- 
pillars, all  of  which  had  hatched  from  eggs  deposited  upon  the 
occasional  wild-cherry  tree  which  was  present.  Several  such  strips 
were  visited  at  about  the  time  when  the  caterpillars  elsewhere  were 
beginning  to  pupate,  and  not  a  single  living  caterpillar  or  pupa 
could  be  found  amongst  the  thousands  of  dead  and  decomposing 
remains  of  the  victims  of  overpopulation.  These  were  but  a  repeti- 
tion of  conditions  as  observed  a  few  miles  north  in  New  Hampshire 
12  years  ago.  How  frequently  similar  conditions  occurred  during 
the  intervening  period  is  not  known. 

In  addition  to  those  species  mentioned  in  the  preceding  pages, 
quite  a  number  of  other  leaf-feeding  Lepidoptera  have  been  more  or 
less  casually  studied  in  a  less  comprehensive  but  at  the  same  time  a 
careful  manner. 

PARASITISM  AS  A  FACTOR  IN  INSECT  CONTROL. 

In  reviewing  the  results  of  these  studies,  the  fact  is  strikingly 
evident  that  parasitism  plays  a  very  different  pari  in  the  economy 
of  different  bosts.  Some  habitually  support  a  parasitic  fauna  both 
abundant  and  varied,  while  others  are  subjected  to  attack  by  only 
a,  limited  Dumber  of  parasites,  the  most  abundant  of  which  is  rela- 
tively uncommon.  No  two  of  the  lepidopterous  hosts  studied, 
unless  they  chanced  to  be  congeneric  and  practically  identical  in 
habit  and  life  history,  were  found  to  be  victimized  by  exactly  the 
same  species  of  parasites.  Neither  are  the  same  species  apt  to  occur 
in  connection  with  the  same  host  in  the  same  relative  abundance, 
one  to  another,  year  after  year  in  the  same  locality,  nor  in  two 
different  localities  the  same  year. 

At  the  same  time  there  are  certain  features  in  the  parasitism  of 
each  species  which  are  common  to  each  of  the  others,  whether  these 
be  arctiid,  liparid,  lasiocampid,  tortricid,  saturniid,  or  tineid,  one  of 
the  most  common  of  which  is  that  each  host  supports  a  variety  of 
parasites,  oftentimes  differing  among  themselves  to  a  remarkable 
degree  in  habit,  natural  affinities,  and  methods  of  attack.  Depart- 


106  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

ures  from  this  rule  have  not  been  encountered  among  the  defoliating 
Lepidoptera  as  yet,  and  while  exceptions  will  probably  be  found  to 
exist,  they  will  doubtless  remain  exceptions  in  proof  of  the  rule. 
From  this  the  rather  obvious  conclusion  has  been  drawn,  that  to 
be  effective  in  the  case  of  an  insect  like  the  gipsy  moth  or  the  brown- 
tail  moth,  parasitic  control  must  come  about  through  a  variety  of 
parasites,  working  together  harmoniously,  rather  than  through  one 
specific  parasite,  as  is  known  to  be  the  case  with  certain  less  spe- 
cialized insects,  having  a  less  well-defined  seasonal  history.  To 
speak  still  more  plainly,  it  is  believed  that  the  successful  conclusion 
of  the  experiment  in  parasite  introduction  now  under  consideration 
depends  upon  whether  or  not  we  shall  be  able  to  import  and  establish 
in  America  each  of  the  component  parts  of  an  effective  " sequence" 
of  parasites.  This  belief  is  further  supported  by  the  undoubted  fact, 
that  in  every  locality  from  which  parasite  material  has  been  received 
abroad,  both  the  gipsy  moth  and  the  brown-tail  moth  are  subjected 
to  attack  by  such  a  group  or  sequence  of  parasites,  of  which  the 
component  species  differ  more  or  less  radically  in  habit  and  in  their 
manner  of  attack. 

In  the  case  of  the  gipsy  moth  and  the  brown-tail  moth  abroad, 
as  well  as  in  that  of  nearly  every  species  of  leaf-feeding  Lepidoptera 
studied  in  America,  there  are  included  among  the  parasites  species 
which  attack  the  eggs,  the  caterpillars,  large  and  small,  and  the 
prepupaB  and  pupae,  respectively.  Frequently,  but  not  always, 
there  are  predatory  enemies,  which,  through  their  ability  to  increase 
at  the  immediate  expense  of  the  insect  upon  which  they  prey,  when- 
ever this  insect  becomes  sufficiently  abundant  to  invite  such  increase, 
are  to  be  considered  as  ranking  with  the  true  facultative  parasites 
when  economically  considered. 

It  is,  therefore,  our  aim  to  secure  the  firm  establishment  in  America 
of  a  sequence  of  the  egg,  the  caterpillar,  and  the  pupal  parasites  of 
the  gipsy  moth  and  brown-tail  moth  as  they  are  found  to  exist 
abroad,  and  until  this  is  either  done  or  proved  to  be  impossible  of 
accomplishment  through  causes  over  which  we  have  no  control,  we 
can  neither  give  up  the  fight  nor  expect  to  bring  it  to  a  successful 
conclusion. 

It  was  stated  a  page  or  two  back  that  some  species  of  insects 
support  a  parasitic  fauna  both  numerous  and  varied,  while  others 
are  subjected  to  attack  by  only  a  limited  number  of  parasites,  none 
of  which  can  be  considered  as  common.  Notwithstanding  the  fact 
that  somewhat  similar  differences  are  discernible  between  the  para- 
sit  ic  fauna  of  the  same  insect  at  different  times  or  under  different 
environment,  it  is  perfectly  safe  to  elaborate  the  original  statement 
still  further  and  to  say  that  some  species  are  habitually  subjected 
to  a  much  heavier  parasitism  than  others.    Unquestionably  the 


PARASITISM  IX  INSECT  CONTROL. 


107 


average  percentage  of  parasitism  of  the  fall  webworm  in  eastern 
Massachusetts,  taken  over  a  sufficiently  long  series  of  years  to  make 
a  fair  average  possible,  is  the  same  as  the  average  would  be  over 
another  similar  series  of  years  in  the  same  general  region.  This 
could  be  said  of  the  larvae  of  any  other  insect  as  well  as  of  that  of 
the  fall  webworm,  but  the  average  percentage  of  parasitism  in  another 
would  most  likely  not  be  the  same,  but  might  be  very  much  larger 
or  very  much  smaller.  To  put  it  dogmatically,  each  species  of  insect 
in  a  country  where  the  conditions  are  settled  is  subjected  to  a  certain 
fixed  average  percentage  of  parasitism,  which,  in  the  vast  majority  of 
instances  and  in  connection  with  numerous  other  controlling  agencies, 
results  in  the  maintenance  of  a  perfect  balance.  The  insect  neither 
increases  to  such  abundance  as  to  be  affected  by  disease  or  checked 
from  further  multiplication  through  lack  of  food,  nor  does  it  become 
extinct,  but  throughout  maintains  a  degree  of  abundance  in  relation 
to  other  species  existing  in  the  same  vicinity,  which,  when  averaged 
for  a  long  series  of  years,  is  constant. 

In  order  that  this  balance  may  exist  it  is  necessary  that  among 
the  factors  which  work  together  in  restricting  the  multiplication 
of  the  species  there  shall  be  at  least  one,  if  not  more,  which  is 
what  is  here  termed  facultative  (for  want  of  a  better  name),  and 
which,  by  exerting  a  rot  raining  influence  which  is  relatively  more 
effective  when  other  conditions  favor  undue  increase,  serves  to  pre- 
vent it.  There  are  a  very  large  number  and  a  great  variety  of 
factors  of  more  or  less  importance  in  effecting  the  control  of  defoli- 
ating caterpillars,  and  to  attempt  to  catalogue  them  would  be  futile, 
but  however  closely  they  may  be  scrutinized  very  few  will  he  found 
to  fall  into  the  class  with  parasitism,  which  in  the  majority  of 
instances,  though  not  in  all.  is  truly  "facultative.'* 

A  very  large  proportion  of  the  controlling  agencies,  such  as  the 
destruction  wrought  by  storm,  low  or  high  temperature,  or  other 
climatic  conditions,  is  to  be  classed  as  catastrophic,  since  they  are 
wholly  independent  in  their  activities  upon  whether  the  insect  which 
incidentally  suffers  is  rare  or  abundant.  The  storm  which  destroys 
10  caterpillars  out  of  50  which  chance  to  be  upon  a  tree  would  doubt- 
less have  destroyed  20  had  there  been  too  present,  or  100  had  there 
been  500  present.  The  average  percentage  of  destruction  remains 
the  same,  no  matter  how  abundant  or  how  near  to  extinction  the 
insect  may  have  become. 

Destruction  through  certain  other  agencies,  notably  by  birds  and 
other  predators,  works  in  a  radically  different  manner.  These 
predators  are  not  directly  affected  by  the  abundance  or  scarcity  of 
any  single  item  in  their  varied  menu.  Like  all  other  creatures  they 
arc  forced  to  maintain  a  relatively  constant  abundance  among  the 


108 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


other  forms  of  animal  and  plant  life,  and  since  their  abundance  from 
year  to  year  is  not  influenced  by  the  abundance  or  scarcity  of  any 
particular  species  of  insect  among  the  many  upon  which  they  prey 
they  can  not  be  ranked  as  elements  in  the  facultative  control  of  such 
species.  On  the  contrary,  it  may  be  considered  that  they  average 
to  destroy  a  certain  gross  number  of  individuals  each  year,  and 
since  this  destruction  is  either  constant,  or,  if  variable,  is  not  corre- 
lated in  its  variations  to  the  fluctuations  in  abundance  of  the  insect 
preyed  upon,  it  would  most  probably  represent  a  heavier  percentage 
when  that  insect  was  scarce  than  when  it  was  common.  In  other 
words,  they  work  in  a  manner  which  is  the  opposite  of  "  facultative" 
as  here  understood. 

In  making  the  above  statement  the  fact  is  not  for  a  moment  lost 
to  sight  that  birds  which  feed  with  equal  freedom  upon  a  variety  of 
insects  will  destroy  a  greater  gross  number  of  that  species  which 
chances  to  be  the  most  abundant,  but  with  the  very  few  apparent 
exceptions  of  those  birds  which  kill  for  the  mere  sake  of  killing  they 
will  only  destroy  a  certain  maximum  number  all  told.  A  little 
reflection  will  make  it  plain  that  the  percentage  destroyed  will 
never  become  greater,  much  if  any,  as  the  insect  becomes  more  com- 
mon, and,  moreover,  that  after  a  certain  limit  in  abundance  is  passed 
this  percentage  will  grow  rapidly  less.  A  natural  balance  can  only 
be  maintained  through  the  operation  of  facultative  agencies  which 
effect  the  destruction  of  a  greater  proportionate  number  of  indi- 
viduals as  the  insect  in  question  increases  in  abundance. 

Of  these  facultative  agencies  parasitism  appears  to  be  the  most 
subtle  in  its  action.  Disease,  whether  brought  about  by  some 
specific  organism,  as  with  the  brown-tail  moth,  or  through  insuffi- 
cient or  unsuitable  food  supply  without  the  intervention  of  any 
specific  organism,  as  appears  at  the  present  time  to  be  the  case  with 
the  gipsy  moth,  does  not  as  a  rule  become  effective  until  the  insect 
has  increased  to  far  beyond  its  average  abundance.  There  are 
exceptions  to  this  rule,  or  appear  to  be,  but  comparatively  only  a 
very  few  have  come  to  our  immediate  attention.  Finally,  i  famine 
and  starvation  must  be  considered  as  the  most  radical  means  at 
nature's  disposal,  whereby  insects,  like  the  defoliating  Lepidoptera, 
are  finally  "brought  into  renewed  subjugation. 

With  insects  like  the  gipsy  moth  and  the  brown-tail  moth  disease 
docs  not  appear  to  become  a  factor  until  a  degree  of  abundance  has 
been  reached  which  makes  the  insect  in  question,  ipso  facto,  a  pest. 
Whether  in  the  future  methods  will  be  devised  for  artificially  ren- 
dering such  diseases  more  quicklj  effective,  remains  to  be  determined 
through  actual  experimental  work  continued  over  a  considerable 
number  of  years. 


RATE  OF  INCREASE  OF  GIPSY  MOTH. 


109 


In  effect,  the  proposition  is  here  submitted  as  a  basis  for  further 
discussion  that  only  through  parasites  and  predators,  the  numerical 
increase  of  which  is  directly  affected  by  the  numerical  increase  of 
the  insect  upon  which  they  prey,  is  that  insect  to  be  brought  under 
complete  natural  control,  except  in  the  relatively  rare  instances  in 
which  destruction  through  disease  is  not  dependent  upon  super- 
abundance. 

The  present  experiment  in  parasite  introduction  was  undertaken 
and  has  been  conducted  on  the  assumption  that  there  existed  in 
America  all  of  the  various  elements  necessary  to  bring  about  the 
complete  control  of  the  gipsy  moth  and  the  brown-tail  moth,  except 
their  respective  parasites.  Believing  that  this  stand  was  correctly 
taken,  much  time  has  been  devoted  to  a  consideration  of  the  extent 
to  which  these  pests  are  already  controlled  through  natural  agencies 
already  in  operation.  The  fact  that  both  insects  have  increased 
steadily  and  rapidly  in  every  locality  in  which  they  have  become 
established  and  where  adequate  suppressive  measures  have  not 
been  undertaken,  until  they  have  reached  a  stage  of  abundance  far 
in  excess  of  that  which  prevails  in  most  countries  abroad,  renders 
superfluous  further  comment  upon  the  present  ineffectiveness  of 
these  agencies.  The  difference  between  the  rate  at  which  they 
have  averaged  to  increase  in  localities  where  they  have  become 
established  and  their  potential  rate  of  increase  as  indicated  by  the 
number  of  eggs  deposited  by  the  average  female  should  indicate 
very  accurately  the  efficiency  of  such  agencies,  and  the  difference 
between  the  actual  rate  of  increase  and  no  increase  similarly  indicates 
the  amount  of  additional  control  which  must  be  exerted  by  the  para- 
sites if  their  numbers  are  to  be  kept  at  an  innocuous  minimum. 

THE  RATE  OF  INCREASE  OF  THE  GIPSY  MOTH  IN  NEW  ENGLAND. 

The  potential  rate  of  increase  as  determined  by  the  number  of 
eggs  deposited  by  the  average  female  of  the  gipsy  moth  varies  con- 
siderably under  different  circumstances,  and  affords  an  interesting 
example  of  a  phase  of  facultative  control  not  touched  upon  in  the 
last  chapter.  When  the  exhaustive  studies  into  its  life  and  habits 
were  conducted  under  the  general  supervision  of  the  Massachusetts 
State  Board  of  Agriculture  during  the  final  decade  of  the  last  century, 
it  was  determined  that  the  number  was  between  450  and  600. 

In  the  opinion  of  some,  the  fecundity  of  the  gipsy  moth  has  dis- 
tinctly decreased  during  the  14  years  which  have  elapsed  since  the 
publication  of  the  report  in  which  these  figures  were  given,  and  in 
order  to  determine  the  point  a  considerable  number  of  egg  masses 
was  collected  during  the  winter  of  1908-9  and  the  eggs  carefully 
counted.  It  was  found  that  in  those  from  the  older  infested  terri- 
tory or  from  outlying  colonies  where  the  moth  was  particularly 


110 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


abundant,  the  number  of  eggs  to  a  mass  averaged  considerably  less 
than  300.  In  egg  masses  from  outlying  districts  where  the  infesta- 
tion was  new,  and  where  the  moth  had  never  reached  its  maximum 
abundance,  the  average  in  a  few  masses  counted  was  slightly  in 
excess  of  500.  The  number  is,  however,  very  variable,  and  the 
character  of  food  and  the  meteorological  conditions  during  the  feed- 
ing period  of  the  caterpillars  are  doubtless  important  features.  Hot 
weather  during  June  forces  the  development  of  the  caterpillars  and 
they  do  not  become  large.  Small  moths  deposit  fewer  eggs  rather 
than  smaller  eggs.  It  is  possible  that  there  is  actually  a  decrease  in 
the  fecundity  of  moths  brought  about  by  our  short  and  ardent  sum- 
mers, but  for  the  present  it  is  not  proved,  and  it  is  believed  that 
whenever  abundance  of  the  insect  is  sufficiently  reduced  the  original 
rate  of  multiplication  will  prevail.  The  point  is  one  well  worthy  of 
further  investigation,  but  for  the  present  the  potential  rate  of 
increase,  provided  no  controlling  factors  whatever  are  operative,  will 
be  considered  as  250-fold  annually. 

The  best  information  available  as  to  the  rate  of  increase  of  the 
gipsy  moth  actually  prevailing  in  Massachusetts  is  contained  in  the 
report  entitled  "The  Gypsy  Moth,"  by  Mr.  Edward  H.  Forbush  and 
Dr.  C.  H.  Fernald,  which  was  published  under  the  direction  of  the 
board  of  agriculture.  These  authorities,  in  their  discussion  of  the 
matter,  say  as  follows: 

The  study  of  the  increase  and  dissemination  of  the  gipsy  moth  in  Massachusetts 
is  most  interesting.  Perhaps  there  never  has  been  a  case  where  the  origin  and 
advance  of  an  insect  could  be  more  readily  traced.  As  the  moth  appears  to  be  con- 
fined as  yet  to  a  comparatively  small  area,  and  as  the  region  has  been  examined 
more  or  less  thoroughly  for  five  successive  years,  the  opportunities  offered  for  the 
study  of  the  multiplication  and  distribution  of  the  insect  have  been  unequaled. 

When  it  is  considered  that  the  number  of  eggs  deposited  by  the  female  averages 
from  450  to  600,  that  1,000  caterpillars  have  been  seen  to  hatch  from  a  single  egg 
cluster,  and  that  at  least  one  egg  cluster  has  been  found  containing  over  1.400  eggs, 
there  can  be  no  doubt  that  the  reproductive  powers  of  the  moth  are  enormous.  Mr. 
A.  II.  Kirkland  has  made  calculations  which  show  that  in  eight  years  the  unre- 
stricted increase  of  a  single  pair  of  gipsy  moths  would  be  sufficient  to  devour  all 
vegetation  in  the  United  States.  This,  of  course,  could  never  occur  in  nature,  and 
is  mentioned  here  merely  to  give  an  idea  of  the  reproductive  capacity  of  the  insect. 

It  seems  remarkable  at  first  sight  that  an  insect  of  such  reproductive  powers,  which 
had  been  in  existence  in  the  State  for  20  years,  unrestrained  by  any  organized  effort 
on  the  part  of  man,  did  not  spread  over  a  greater  territory  than  30  townships,  or  about 
220  square  miles.  Some  of  the  causes  which  at  first  checked  its  increase  and  lim- 
ited its  diffusion  in  Medford  have  already  been  set  forth.  Most  of  the  checks  which 
at  first  served  to  prevent  the  excessive  multiplication  of  the  gipsy  moth  in  Medford 
operate  effectively  to-day  wherever  the  species  is  isolated.  True,  it  has  now  become 
acclimated.  But  any  small  isolated  moth  colony  still  suffers  greatly  from  the  attacks 
of  its  natural  enemies  and  from  the  struggle  with  other  adverse  influences  which 
encompass  it.  The  normal  rate  of  increase  in  such  isolated  colonies  as  are  found 
to-day  in  the  outer  towns  of  the  infested  district  seems  to  be  small.  The  annual 
increase  can  be  readily  ascertained  by  noting  the  relative  number  of  egg  clusters  laid 


RATE  OF  INCREASE  OF  GIPSY  MOTH. 


Ill 


in  successive  years,  the  unhatehed  or  latest  clusters  being  easily  distinguished  from 
the  hatched  or  "old"  clusters,  and  the  age  of  these  latter,  whether  one.  two,  three, 
or  more  years,  being  indicated  by  their  state  of  preservation.  The  ratio  of  the  aver- 
age annual  increase  of  10  such  colonies  was  found  to  be  6.42;  that  is,  six  or  seven 
egg  clusters  on  an  average  may  be  found  in  the  second  season  to  one  of  the  first 
season . 

If  the  number  of  eggs  deposited  by  the  average  female  moth  be 
set  at  500,  and  if  the  sexes  of  her  progeny  are  equally  divided,  a 
potential  increase  of  250-fold  for  each  annual  generation  is  provided 
for.  Under  complete  control  only  one  pair  of  moths  would  average 
to  be  produced  from  each  mass  of  eggs  deposited,  and  since  each  egg 
represents  an  individual  embryo,  all  but  2  of  each  500  must  fail  to 
reach  full  maturity.  Reduced  to  percentage  this  is  equivalent  to 
the  survival  of  0.4  per  cent  and  the  destruction  of  99.6  per  cent  of 
the  gipsy  moths  in  one  stage  or  another  every  year.  Since  the  total 
number  of  gipsy  moths  in  any  locality  can  not  possibly  be  computed, 
the  only  method  by  which  mortality  through  any  cause  may  be 
expressed  is  on  this  basis. 

It  will  surprise  many  who  have  not  given  the  matter  considera- 
tion to  learn  what  an  extraordinary  ajijKirtnt  mortality  it  requires  to 
offset  a  potential  increase  of  250-fold.  The  gipsy-moth  caterpillars 
molt  live  or  six  times  after  t  hey  batch  and  before  they  change  to  pupa?, 
making  the  number  of  caterpillar  stages  >ix  or  seven.  If  through 
natural  controlling  agencies  50  per  cent  of  the  young  caterpillars 
were  destroyed  in  the  iirst  stage  before  they  had  molted,  and  this 
was  followed  by  similar  destruction  of  another  50  per  cent  in  the 
second  stage,  and  so  on  through  the  third,  fourth,  fifth,  sixth,  and 
seventh  stages,  respectively,  and  in  addition  25  percent  of  the  pupa? 
and  25  per  cent  of  the  adults  before  depositing  their  eggs  were  simi- 
larly destroyed,  it  would  still  permit  of  a  slight  annual  increase. 

The  following  table  (if  the  incongruity  of  fractions  as  applied  to 
insects  may  be  overlooked)  indicates  the  number  of  survivors  of  each 
stage  resulting  from  the  hatching  of  a  mass  of  500  eggs: 


Stage. 

Number. 

Ix>ss. 

Number 
remain- 
ing. 

Potential  increase. 

Eggs  

500 
500 
250 
125 

62 

31 

15.5 
7.75 
3.875 
2. 906 

/'<  r  ct  lit. 
0 
50 
50 
50 
50 
50 
50 
50 
25 
25 

500 
250 
125 

62 

31 

15.5 
7.75 
3.  875 
2. 906 
2. 179 

250  fold. 
125  fold. 
62  fold. 
31  fold. 
15.5  fold. 
7.75  fold. 
3.875  fold. 
2.906  fold. 
2.179  fold. 
1.634  fold. 

Caterpillars  

First  

Do  

Second  

Do  

Third  

Do  

Fourth  

Do  

Fifth   

Do  

Sixth  

Do  

Seventh  

PupfT  

Adults  

To  give  another  illustration:  The  life  of  the  gipsy-moth  caterpillar 
is  approximately  seven  weeks.    If  beginning  on  the  first  day  after 


112  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


hatching  and  on  every  day  thereafter  during  this  period  a  decrease 
in  numbers  of  10  per  cent  should  be  brought  about  through  natural 
causes,  there  would  still  be  enough  survivors  to  permit  of  a  substan- 
tial increase  in  the  abundance  of  the  insect. 

Twelve  gipsy  moths  (6  pairs)  from  each  egg  mass  would  be  suffi- 
cient to  provide  for  a  sixfold  annual  increase.  If  reference  be  made 
to  the  preceding  table,  it  will  be  seen  that  if  all  destruction  ceased 
after  the  caterpillars  had  reached  the  fourth  stage,  the  survivors 
would  permit  of  slightly  in  excess  of  sixfold  increase;  that  is,  the 
mortality  during  the  first  to  the  fourth  stage,  inclusive,  with  a  part 
of  that  which  resulted  during  the  fifth  stage,  would  be  sufficient  to 
account  for  all  of  the  control  at  present  exerted  by  natural  agencies 
in  New  England,  and  this  gives,  at  the  same  time,  an  idea  as  to  the 
amount  of  additional  control  which  the  parasites  must  accomplish  if 
they  are  to  become  effective. 

The  conditions  under  which  the  gipsy  moth  was  studied  at  the 
time  when  the  material  for  the  report  just  quoted  was  accumulated 
were,  for  the  most  part,  abnormal.  In  only  relatively  few  localities 
was  it  allowed  to  increase  undeterred,  and  there  were  relatively  very 
few  examples  of  unrestricted  increase  to  the  point  when  defoliation 
resulted.  This,  in  part,  explains  what  seems  to  be  an  element  of 
indecision  concerning  the  character  of  conditions  which  favored  more 
rapid  increase  of  the  moth,  as  quoted  below,  from  the  same  source. 

CONDITIONS  FAVORING  RAPID  INCREASE. 

When  any  colony  under  average  normal  conditions  has  grown  to  a  considerable 
size  and  then  received  an  added  impetus  from  exceptionally  favorable  conditions,  its 
power  of  multiplication  and  its  expansive  energy  are  greatly  augmented,  and  its 
annual  increase  arises  above  all  calculations.  1  Under  such  influences  hundreds  of 
egg  clusters  will  appear  in  the  fall  where  few  were  to  be  seen  in  the  spring,  and  thou- 
sands are  found  where  scores  only  were  known  before.  It  is  probable  that  the  season 
of  1889  was  particularly  favorable  for  the  moth's  increase.  The  season  of  1894  and 
that  of  1895  appear  also  to  have  furnished  conditions  especially  favorable  for  an 
abnormal  multiplication  of  the  insect. 

The  operation  of  the  causes  of  these  sudden  outbreaks  is  not  understood.  It  is 
evident,  however,  that  the  warm,  pleasant  spring  weather  of  the  past  two  years  (1894 
and  1895)  hastened  the  development  of  the  caterpillars,  thereby  shortening  their  term 
of  life.  The  length  of  life  of  the  caterpillars  varies  from  six  to  twelve  weeks.  During 
cold,  rainy  weather  the  caterpillars  eat  little  and  grow  slowly.  During  warm,  dry 
weather  they  consume  much  more  food  and  grow  with  great  rapidity.  In  the  unusu- 
ally warm  spring  and  early  summer  of  1895  many  of  the  caterpillars  molted  a  less 
number  of  times  than  usual,  and  their  length  of  life  did  not  exceed  six  or  seven  weeks- 
Under  these  conditions  they  proved  more  quickly  injurious  to  foliage  than  in  a  more 
normal  season,  and  were  more  completely  destructive  within  any  given  area  in  which 
their  numbers  were  great.    And  they  were  not  so  long  exposed  to  the  attacks  of  their 

i  The  increase  of  these  large  colonies  seems  to  he  limited  only  by  the  supply  of  food.  Whenever  food 
becomes  scarce  many  of  the  moths  are  less  prolific.  The  larv;v  which  do  not  find  sufficient  food  either  die 
or  develop  early,  and  the  female  moths  lay  fewer  eggs  than  those  which  transform  from  well-nourished 
caterpillars. 


RATE  OF  INCREASE  OF  GIPSY  MOTH. 


113 


enemies.  While  it  may  be  true  that  the  parasitic  enemies  of  the  moth  will  also  develop 
rapidly  under  conditions  that  hasten  the  growth  of  their  host,  birds  and  other  verte- 
brate enemies  will  secure  fewer  of  the  moths  in  6  or  7  weeks  than  in  10  or  12.  It  is 
believed  that  dry  weather  is  unfavorable  for  vegetable  parasites  of  insects,  but  to 
what  extent  the  caterpillars  are  affected  by  them  in  a  humid  season  it  is  impossible 
t<>  say. 

The  past  two  years  have  been  "cankerworm  years"  in  the  infested  region.  Many 
of  the  birds  which  habitually  feed  on  the  caterpillars  of  the  gipsy  moth  have  been 
largely  occupied  during  May  and  the  early  part  of  June  in  catching  cankerworms, 
which  they  seem  to  prefer,  turning  their  attention  to  the  gipsy-moth  caterpillars  in 
the  latter  part  of  June  and  July,  when  the  cankerworms  have  disappeared.  The 
birds,  therefore,  have  not  been  as  useful  in  checking  the  increase  of  the  gipsy  moth 
as  in  years  when  the  cankerworms  were  less  numerous. 

A  few  of  the  restraining  influences  which  have  been  less  active  than  usual  during 
the  past  two  years  have  been  mentioned,  and  possibly  many  others  have  escaped 
observation,  but  those  u'iven  serve  in  a  measure  to  explain  the  unusual  increase  of  the 
moth.  It  is  during  such  seasons  that  its  dest  met  i  veness  is  most  apparent.  It  is  then 
that  the  groves  and  forests  are  stripped  of  their  leaves,  and  whole  rows  of  trees  in 
orchards  and  along  highways  appear  to  have  I  n  stripped  in  a  single  night. 

The  conditions  as  described  seem  to  be  comparable  to  those  pre- 
vailing at  the  present  time,  and  at  the  same  time  to  l>c  inadequately 
explained.  Repeatedly  personal  observations  have  been  made  which 
indicate  beyond  the  >hadow  of  a  doubt  that  under  certain  circum- 
stances the  gipsy  moth  has  increased  at  a  rate  very  far  in  excess  of 
sixfold  annually  at  the  present  time.  Counts  of  old  egg  masses  as 
compared  with  those  newly  laid,  in  several  localities,  in  the  spring 
of  1908  and  each  spring  subsequently,  have  shown  positively  that 
an  increase  of  at   least   twentyfold  was  not   uncommon.     In  fact, 

unless  an  unduly  large  number  of  old  egg  masses  was  concealed,  it 
could  be  said  with  equal  certainty  that  increase  sometimes  amounted 
to  fiftyfold  in  the  course  of  a  single  generation.  The  arguments  pre- 
sented by  Forbush  and  Kernald,  who  evidently  observed  something 
very  similar,  and  who  were  inclined  to  credit  it  to  seasonal  or  climatic 
conditions  ( in  part  at  least ),  do  not  stand,  in  view  of  t  he  fact  that  the 
rate  of  increase  differs  extraordinarily  in  localities  nearly  adjacent  to 
where  the  conditions  are  practically  identical,  saving  only  the  varying 
abundance  of  the  moth;  this  latter,  it  may  be  noted,  has  in  each 
instance  corresponded  roughly  and  in  direct  ratio  to  the  rate  of  in- 
crease. The  fact  was  not  considered  to  be  of  more  than  coincidental 
interest  at  first,  but  Later,  when  an  attempt  was  made  to  classify 
according  to  their  manner  of  operation,  the  various  factors  which 
were  already  responsible  for  the  partial  control  of  the  gipsy  moth  in 
New  England,  the  correlation  between  relative  abundance  and  rate 
of  increase  recurred  and  seemed  to  afford  excellent  support  to  the 
contention  which  has  been  made  as  to  the  part  which  birds  and  most 
other  predators  play  in  bringing  this  about. 
95677°— Bull.  91— 11  8 


114  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

Without  attempting  to  go  into  the  details  of  rather  elaborate  cal- 
culations, which  were  made  for  the  purpose  of  bringing  out  this  point 
more  graphically,  attention  is  merely  called  to  the  three  divisions 
into  which  the  elements  operative  in  the  natural  control  of  any  insect 
naturally  fall  as  they  were  outlined  in  the  preceding  section.  These 
are,  first,  the  catastrophic  (storms,  etc.),  which  result  in  the  destruc- 
tion of  a  certain  fixed  percentage,  irrespective  of  the  abundance  of 
the  insect;  second,  that  represented  by  the  birds,  most  other  preda- 
tors, and  a  part  of  the  parasites  which  encompass  the  destruction  of 
a  certain  gross  number,  rather  than  of  any  given  percentage  each 
year  or  generation;  third,  the  facultative  agencies,  of  which  certain 
parasites  are  considered  to  be  typical,  which  increase  in  efficiency  as 
the  insect  increases  in  abundance. 

The  elements  composing  this  last  group  are  absent  in  New  England, 
or,  rather,  those  elements  which  are  present  (disease  and  starvation) 
and  which  do  not  properly  belong  to  it,  are  inoperative  until  a  state 
of  extreme  abundance  is  attained. 

Such  control  as  is  effected  by  existing  agencies  would  therefore  fall 
into  one  or  the  other  of  the  first  two  groups  mentioned,  and  since 
both  groups  together  are  obviously  inefficient,  even  when  the  moth 
is  scarce,  that  due  to  the  operation  of  the  elements  falling  in  the 
second  group  would  become  relatively  less  efficient  as  the  time  went 
on  and  the  moth  increased.  This,  it  is  believed,  is  actually  what  has 
happened  and  what  is  happening  each  year  in  each  of  the  very 
numerous  outlying"  colonies  of  the  gipsy  moth  throughout  the  more 
recently  infested  territory,  and  thus  the  larger  rate  of  increase  is 
explained. 

As  a  matter  of  fact,  there  is  reason  to  believe  that  the  average  rate 
of  increase  during  the  first  few  years  immediately  following  the  intro- 
duction of  the  moth  in  a  new  locality  is  actually  less  than  sixfold 
annually,  and  that  it  may  even  be  as  low  as  threefold,  or  perhaps  less. 
In  any  case,  there  is  a  stage  in  the  progress  of  the  moth  in  which  the 
average  is  no  greater  than  that  recorded  by  Forbush  and  Fernald, 
and  there  is  no  longer  room  for  doubt  that  the  lowest  rate  of  increase 
is  in  localities  where  the  moth  is  relatively  a  rare  or  uncommon 
insect  for  the  time  being,  while  the  highest  occurs  in  localities  where 
the  moth  is  rapidly  approaching  its  maximum  abundance. 

AMOUNT  OF  ADDITIONAL  CONTROL  NECESSARY  TO  CHECK  THE 
INCREASE  OF  THE  GIPSY  MOTH  IN  AMERICA. 

It  was  evident  in  1907,  as  it  is  now,  that  the  problem  of  the  intro- 
duction of  parasites  was  far  from  being  as  simple  as  it  might  appear 
to  be  upon  its  surface  and  as  it  evidently  did  appear  to  be  to  some 
who  were  at  that  time  agitating  for  a  radical  change  in  the  methods 
adopted  for  its  solution.     It  was  plain  that  the  expense  incident  to 


VMOTXT  OF  CONTROL  NEEDED  FOR  GIPSY  MOTH. 


115 


the  actual  work  of  importation  was  going  to  be  considerably  more 
than  had  been  expected  two  years  before  and  that  practical  results 
could  not  possibly  be  achieved  until  long  after  the  time  originally 
predicted.  Additional  information  upon  the  biology  and  habits  of 
each  of  the  several  parasites,  if  not  necessary  in  every  instance,  was 
necessary  in  some  and  desirable  in  all,  and  here  again  additional 
expenditure  became  imperative.  Furthermore,  the  situation  was 
such  as  to  make  of  very  doubtful  advisability  the  indiscriminate 
importation  of  very  large  quantities  of  parasite1  material  before  a 
belter  knowledge  of  the  parasites  themselves  had  been  secured.  The 
repetition  of  the  very  large  shipment  of  brown-tail  hibernating  nests 
winter  after  winter,  as  will  be  described  in  another  chapter,  is  an 
instance  in  point.  Had  we  been  in  possession  of  a  complete  knowl- 
edge of  the  parasites  hibernating  in  those  webs  at  the  beginning,  per- 
haps one  winter's  importation  would  have  been  sufficient. 

There  was  no  certainty  that  the  results  of  the  technical  studies  as 
conducted  at  the  American  laboratory  would  be  sufficiently  full  and 
complete  to  answer  OUT  purposes  and  make  possible  the  intelligent 
continuation  of  the  work.  Should  we  fail  in  this  respect,  the  only 
alternative  to  a  discontinuation  of  the  introduction  work  in  advance 
of  its  logical  conclusion  was  the  establishment  of  a  laboratory  abroad, 
at  a  considerable  expenditure. 

With  these  several  reflect  ions,  il  was  inevitable  that  the  advisability 
of  continuing  the  work  beyond  the  time  limit  originally  set  should 
come  into  question.  Accordingly .  in  anticipation  of  the  necessity  for 
making  a  decision  when  the  time  for  it  should  arrive,  the  whole 
proposition  was  subjected  anew  to  the  closest  sort  of  scrutiny  from 
every  point  of  view  . 

The  successful  consununat ion  of  the  work  involved,  first  of  all,  the 
establishment  in  America  of  a  group  of  parasites  or  other  natural 
enemies  sufficiently  powerful  to  meet  and  offset  the  prevailing  rate  of 
increase  of  the  gipsy  moth.  This,  as  determined  by  Forbush  and 
Fernald,  was  at  least  sixfold  annually:  as  determined  by  actual 
observation  in  the  field,  it  was  often  far  in  excess  of  sixfold. 
Before  the  continuation  of  the  work  could  be  recommended  it  was 
absolutely  necessary  to  arrive,  first,  at  some  conclusion  as  to  the 
amount  of  parasitism  (gauged  on  the  percentage  basis)  which  would 
be  required  in  order  to  offset  this  increase  and  maintain  the  gipsy 
moth  at  an  innocuous  minimum:  and,  second,  whether  parasitism 
to  such  an  extent  actually  prevailed  abroad  or  whether  natural  con- 
trol in  those  localities  where  it  was  obviously  effected  was  due  to  the 
increased  efficiency  of  other  agencies. 

In  so  far  as  the  first  proposition  was  concerned,  it  was  obvious  from 
the  beginning  that  if  enough  egg  masses  could  be  destroyed  each  fall 
so  that  the  number  remaining  would  be  no  greater  than  that  which  had 


116 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


been  present  in  the  spring  the  insect  could  never,  by  any  possibility, 
increase  beyond  the  abundance  then  prevailing.  If  the  increase  each 
year  was  6  egg  masses  for  each  1  of  the  year  before,  it  was  merely 
necessary  to  destroy  5  out  of  every  6  in  order  to  maintain  the  status 
quo.  If  the  increase  was  tenfold,  the  destruction  of  9  out  of  every  10 
egg  masses  would  be  required,  etc.  The  same  would  obtain  if  5  out 
of  every  6  or  9  out  of  every  10  eggs  in  each  and  every  mass  were 
similarly  destroyed. 

Reduced  to  percentages,  this  would  be  equivalent  to  the  destruction 
of  83.33  per  cent  or  of  90  per  cent,  respectively,  a  rate  of  parasitism 
which  was  physically  an  impossible  accomplishment  for  the  egg 
parasites  alone.  Additional  parasitism  of  the  caterpillars  or  pupae 
would  be  a  requisite  to  success,  and  such  parasitism  would  of  neces- 
sity be  similarly  limited  in  many  instances  through  circumstances  as 
completely  beyond  our  control  as  the  physical  inability  of  Schedius  or 
Anastatus  to  parasitize  more  than  the  uppermost  layer  of  eggs  in  each 
mass  attacked.  Without  attempting  to  go  into  any  of  the  details 
of  the  processes  by  which  conclusions  were  reached,  it  was  finally 
determined,  beyond  any  doubts  arising  through  arguments  which 
have  been  presented  up  to  the  present  time,  that  an  aggregate  parasit- 
ism of  83.33  per  cent  would  be  absolutely  necessary  if  a  sixfold 
increase  was  to  be  met,  but  that  it  made  no  difference  whether  this 
was  brought  about  by  one  species  or  two  or  a  dozen,  or  whether  they 
attacked  the  egg,  the  caterpillar,  or  the  pupae.  It  was  also  deter- 
mined that  the  aggregate  percentage  necessary  could  not  be  secured 
by  simply  adding  together  the  figures  representing  the  parasitism 
resulting  through  attack  by  each  of  two  or  more  species.  It  was 
going  to  be  necessary  to  combine  these  several  aggregates  in  a  dif- 
ferent manner.  To  illustrate:  A  50  per  cent  parasitism  of  the  eggs, 
if  it  could  possibly  be  secured,  followed  by  another  50  per  cent  parasit- 
ism of  the  caterpillars,  could  not  by  any  possibility  be  considered  as 
resulting  in  100  per  cent  parasitism  or  complete  extinction,  but  only  in 
50  per  rent  parasitism  added  to  50  per  cent  of  what  remained,  which 
amounted,  in  effect,  to  25  per  cent  of  the  whole.  In  this  manner  an 
aggregate  of  75  per  cent  only  is  secured. 

As  is  illustrated  by  the  table  on  page  III,  it  requires  the  combina- 
tion of  an  imposing  array  of  figures  representing  relatively  small  per- 
centages of  parasitism  in  each  instance  to  acquire  a  sufficiently  large 
aggregate. 

It  was  further  determined  that  any  specific  amount  of  parasitism, 
as  20  per  cent  of  the  eggs,  was  neither  more  nor  less,  but  exactly  as 
effective  as  20  per  cenl  parasitism  of  the  caterpillars  or  pupSB,  in  so  far 
as  ils  value  in  constructing  the  final  aggregate  was  concerned. 

It  can  not  he  denied  that  when  the  validity  of  these  conclusions 
became  established  and  when  in  addition  the  possibility  that  a  much 


EXTENT  OF  GIPSY-MOTH   PARASITISM  ABROAD. 


117 


greater  rate  of  increase  than  sixfold  would  have  to  be  met  and  offset 
before  the  much-to-be-desired  consummation  could  reasonably  be 
expected  the  prospects  looked  rather  discouraging.  Recognition 
of  the  correlation  which  existed  between  increased  abundance  and 
rate  of  increase  served  more  than  anything  else  to  allay  the  doubts 
which  these  reflections  created.  Field  work  in  1908,  1909,  and  1910 
showed  pretty  conclusively  that  a  rate  of  increase  of  not  in  excess  of 
sixfold  and  possibly  considerably  less  prevailed  whenever  the  moth 
was  in  that  state  of  innocuousness  incident  to  the  scarcity  which 
it  was  hoped  to  bring  about  and  maintain  through  the  introduction  of 
the  parasites.  An  aggregate  parasitism  of  So  per  cent  will  almost 
certainly  be  sufficient,  and  it  may  well  be  that  SO  per  cent  or  even 
75  per  cent  will  answer  equally  well.  Much  less  than  75  per  cent  will 
probably  not  be  effective. 

THE  EXTENT  TO  WHICH  THE  GIPSY  MOTH  IS  CONTROLLED 
THROUGH  PARASITISM  ABROAD. 

While  it  is  true  that  the  work  which  has  been  done  for  the  purpose 
of  determining  the  prevailing  rate  of  increase  of  the  gipsy  moth  in 

America  leaves  considerable  to  be  desired  in  the  way  of  exactness,  in 
the  main  the  statements  made  by  Korbush  and  Fernald,  as  confirmed 
and  modified  by  later  observation,  may  be  accepted  as  essentially 

accurate.  It  is  fortunate  that  the  situation  ifi  Q0  worse  than  it  appeal's 
to  be,  for  if  it  wore  necessary  to  undertake  the  work  of  parasite  intro- 
duction with  the  idea  that  the  maximum  rale  of  increase  exhibited  by 
the  gipsy  moth  must  be  met  by  the  parasites,  such  an  unreasonable 
percentage  <>f  parasitism  would  be  demanded  as  to  make  the  propo- 
sition of  Introducing  them  a  decidedly  difficult  task.  As  it  is,  there 
seems  to  be  good  reason  to  believe  that  a  parasitism  amounting  to 
7")  per  cent  will  be  sufficient,  provided  that  it  can  be  maintained 
during  the  periods  when  the  moth  is  relatively  rare.  It  may  be 
that  less  than  that  will  answer  equally  well,  but  it  would  require 
actual  test  or  else  a  much  more  careful  study  of  the  actual  rate  of 
increase  of  the  moth  under  favorable  conditions  to  justify  such 
prophecy.  In  any  event,  85  percent  will  probably  be  amply  efficient, 
if  it  can  be  established  and  maintained  during  all  stages  in  the  abun- 
dance of  the  moth.  Such  a  rate  would  undoubtedly  prevent  the  moth 
from  increasing  to  destructive  abundance  in  new  territory  or  from 
gaining  ground  lost  through  the  activities  of  disease  in  older  infested 
regions. 

Granted  that  it  is  sufficient,  the  question  naturally  arises  as  to 
whether  such  a  degree  of  parasitism  is  to  be  found  abroad  in  coun- 
tries where  the  gipsy  moth  is  present  without  being  considered  as  a 
serious  pest. 


118 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


There  is  veiy  little  published  information  at  hand  bearing  upon 
this  subject,  and  that  which  is  available  is  general  rather  than  defi- 
nite in  its  tenor.  Anyone  who  for  the  first  time  encounters  a  tree 
covered  with  caterpillars  of  the  gipsy  moth  dead  and  dying  through 
the  effects  of  the  "wilt"  disease  is  very  apt  to  think  that  at  last 
the  gipsy  moth  has  met  its  Waterloo,  and  disillusionment  has  only 
come  in  the  present  work  as  the  result  of  several  years'  consecutive 
observations  in  the  same  or  similar  localities.  In  like  manner  the 
observations  of  foreign  entomologists,  or  of  American  entomologists 
traveling  abroad,  as  to  the  actual  effectiveness  of  the  parasites  in 
accomplishing  the  control  of  the  moth  have  to  be  taken  with  a  grain 
of  conservatism.  Parasitism  by  a  species  as  conspicuous  as  Apan- 
teles  Julvipes  to  the  extent  of  50  per  cent  would  undoubtedly  create 
a  most  favorable  impression  and  the  more  conspicuous  parasitized 
caterpillars  would  easily  appear  to  outnumber  the  healthy.  This 
amount  of  parasitism  would  certainly  be  inefficient  in  America  unless 
it  were  supplemented  by  a  much  larger  amount  of  parasitism  by 
other  species. 

On  this  account  it  has  been  necessary  to  depend  very  largely  upon 
the  study  of  the  parasite  material  imported  from  abroad  as  a  source 
for  information  of  this  sort.  From  the  beginning  accurate  notes 
have  been  kept  of  the  many  thousands  of  boxes  of  eggs,  caterpillars, 
and  pupse  of  the  gipsy  moth  and  brown-tail  moth,  in  which  are 
recorded  the  locality  from  which  each  lot  came,  its  condition  on 
receipt,  and  the  number  and  variety  of  parasites  reared  in  each 
instance.  The  records  are  necessarily  based  in  most  instances  upon 
such  information  as  may  be  gained  through  a  study  of  the  condition 
of  the  material  on  receipt  and  the  parasites  reared,  but  in  a  few 
careful  dissection  work  has  been  carried  on  to  determine  the  true 
conditions,  and  thus  to  check  up  the  results  of  the  rearing  work. 
It  has  been  found  that  the  amount  of  dependence  which  can  be 
placed  upon  the  rearing  records  is  relatively  small,  and  that  noth- 
ing more  than  a  general  idea  of  conditions  actually  prevailing  can  be 
gleaned  from  them.  Nearly  always  some  of  the  caterpillars  or  pupae 
arc  dead  or  dying  upon  receipt  as  a  result  of  the  ordeal  through  which 
they  have  passed.  On  the  average,  taking  the  gipsy-moth  material 
from  all  localities,  not  more  than  25  per  cent  has  arrived  in  good 
condition  (when  the  shipment  of  eggs  is  excepted).  The  brown- 
tail  moth  material  lias  averaged  very  much  better,  and  probably  75 
per  cent  lias  been  in  good  condition  on  receipt. 

It  has  been  found  that  sometimes  a  larger  percentage  of  parasites 
than  of  caterpillars  or  pupee  died  en  route,  while  at  other  times  these 
conditions  arc  entirely  reversed,  and  since  dissections  can  not  be 
made  in  every  instance,  it-  has  been  necessary  to  consider  the  para- 
sitism indicated  by  the  notes  upon  two  different  bases,  i.  e.,  that  of  ( 


EXTENT  OF  GIPSY-MOTH  PARASITISM  ABROAD. 


119 


the  number  of  hosts  originally  involved  and  that  of  the  number  suc- 
cessfully completing  their  transformations.  If  from  a  Lot  of  1.000 
brown-tail  caterpillars  250  individuals  of  Parexorista  chelonise  and 
250  moths  are  reared,  it  is  perfectly  safe  to  assume  that  parasitism 
by  Parexorista  amounts  to  more  than  25  per  cent  and  less  than  75 
per  cent.  Further  than  this  nothing  absolutely  definite  may  be  said. 
Exactly  the  same  is  true  of  the  determination  of  prevailing  rates  of 
parasitism  of  native  insects  through  rearing  work. 

On  account  of  the  inadequacy  of  these  methods  when  it  comes  to 
the  point  of  securing  absolutely  authentic  information,  not  nearly  so 
much  is  known  of  the  parasitism  of  the  gipsy  moth  or  of  the  brown- 
tail  moth  abroad  as  is  needed  to  carry  on  the  work  to  its  best  advan- 
tage. This  much,  however,  can  be  said  definitely,  that  in  some 
instances  existing  parasitism  is  sufficient  to  answer  the  requirements 
of  the  situation  in  America :  in  others  it  is  obviously  insufficient;  in 
most  the  results  of  the  study  of  imported  material  are  not  sufficiently 
reliable  to  support  either  contention. 

Here,  again,  was  food  for  serious  consideration  when  it  came  to 
the  point  of  making  definite  recommendations  concerning  the  con- 
tinuation of  the  work.  Would  the  foreign  parasites  certainly  meet 
the  demands  which  would  be  made  upon  them  in  America? 

This  has  been  answered  in  the  affirmative  through  its  considera- 
tion from  quite  a  variety  of  different  viewpoints.  For  one  thing, 
the  lack  of  accurate  information  as  to  the  conditions  under  which  the 
parasite  material  was  originally  collected,  lias  rendered  the  results 
of  its  study  in  America  of  difficult  analysis.  No  one,  for  example, 
would  seriously  question  the  statement  that  the  white-marked  tus- 
sock moth  is  under  well-nigh  perfect  control  in  America  except  in 
cities.  Nevertheless,  if  it  was  desired  to  transport  caterpillars  or 
pupa4  of  this  insect  to  Europe  in  order  that  its  parasites  might  be 
reared,  the  agent  intrusted  with  the  collection  of  the  material  for 
exportation  would  certainly  go  to  the  city  for  it.  and  the  person  who 
received  and  studied  it  upon  the  other  side  w  ould  find  so  few  para- 
sites present  as  to  justify  exactly  the  same  doubts  concerning  the 
parasitism  of  the  tussock  moth  in  America  as  have  actually  arisen 
concerning  the  parasitism  of  the  gipsy  moth  and  the  brow  n-tail  moth 
in  Europe.  The  tussock  moth  is  not  often  subjected  to  the  full 
extent  of  parasitism  necessary  to  effect  its  control  in  any  locality 
from  w  hich  caterpillars  can  be  secured  in  quantity.  It  is  reasonable 
to  suppose  that  something  of  the  same  sort  is  true  of  the  gipsy  moth 
or  of  the  brown-tail  moth. 

Furthermore,  the  study  of  the  tussock  moth  has  resulted  in  demon- 
st  rating  another  fact  which  is  of  peculiar  interest  in  this  connection, 
which  is,  that  the  parasites  which  assist  in  effecting  it<  control  in 
country  districts  where  this  control  is  perfect  are  sometimes  entirely 


120  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

absent  in  the  city.  Something  of  the  same  sort  may  be  true  of  the 
parasites  which  assist  in  effecting  the  control  of  the  gipsy  moth  in 
many  localities  in  Europe  where  it  is  so  uncommon  as  to  make  col- 
lection of  material  for  exportation  in  any  quantity  impossible.  Some 
of  the  most  interesting  lots  of  caterpillars  or  pupae  which  have  been 
received  were  from  such  localities,  and  it  may  well  be  that  there  are 
parasites  abroad  which  have  not  been  received  at  the  laboratory  in 
Massachusetts  in  sufficient  quantity  for  colonization,  and  which  can 
never  be  received  there  until  new  methods  for  collecting  and  import- 
ing them  are  devised,  but  which  at  the  same  time  are  actually  among 
the  important  species.  This  fact  can  only  be  determined  definitely 
by  careful  study  of  the  gipsy  moth  in  localities  where  it  was  not 
sufficiently  abundant  to  permit  of  its  collection  in  large  quantities. 
These  studies,  it  is  hoped,  will  be  instituted  in  1911,  and  so  long  as 
the  gipsy  moth  continues  to  be  a  serious  pest  in  America  the  inves- 
tigation of  its  parasites  abroad  ought  to  be  continued. 

The  ramifications  of  the  parasite  work  have  been  so  many  and  so 
diverse  and  have  led  so  far  afield,  both  literally  and  metaphorically 
speaking,  as  to  make  it  practically  impossible  to  report  upon  it  as  a 
whole  as  fully  as  would  be  desirable  and  practicable  were  it  less 
extensive  and  varied.  A  chapter  might  be  written  upon  the  para- 
sitism of  the  gipsy  moth  and  another  upon  that  of  the  brown-tail 
moth  in  each  of  the  several  countries  in  Europe  from  which  the 
parasite  material  has  been  imported,  but  it  is  wholly  impracticable 
to  do  so.  At  the  same  time,  now  that  a  new  phase  of  the  work  is 
being  entered  upon,  it  will  not  be  out  of  place  to  review  in  some 
slight  detail  the  results  of  the  work  which  has  been  carried  on  in  a 
few  of  the  localities  which,  for  one  reason  or  another,  may  be  selected 
as  of  more  than  general  interest  in  this  immediate  connection,  but 
which  are  at  the  same  time  and  in  another  sense  typical. 

PARASITISM  OF  THE  GIPSY  MOTH  IN  JAPAN. 

From  the  viewpoint  of  gipsy-moth  parasitism  Japan  possesses  a 
peculiar  interest,  because,  if  we  are  to  judge  from  the  reports  of 
those  who  have  been  there  and  incidentally  or  critically  studied  the 
situation,  the  Japanese  gipsy  moth  is  pretty  thoroughly  controlled 
through  natural  agencies,  and  among  these  its  parasites  appear  to 
rank  very  high.  This  is  the  more  interesting  and  encouraging 
because  the  Japanese  race  is  notably  larger  and  at  the  same  time 
more  fecund  than  the  European,  judging  from  counts  as  made  at  the 
laboratory  of  the  number  of  eggs  in  a  mass. 

In  1908,  after  several  unsuccessful  attempts  which  had  been  made 
to  import  its  parasites  had  served  to  domonstrate  the  futility  of  any 
Less  radical  course,  Prof.  Trevor  Kincaid,  of  the  University  of  Wash- 
ington, Seattle,  was  delegated  to  spend  the  summer  there  in  the 


EXTENT  OF  GIPSY-MOTH  PARASITISM  ABROAD. 


121 


interests  of  the  work.  As  a  result  numerous  large  shipments  of 
parasite  cocoons  and  puparia,  as  well  as  of  caterpillars  in  various 
stages  and  of  pupa'  were  received  at  the  laboratory.  The  condition 
of  the  material  on  receipt  compared  more  than  favorably  with  the 
average  of  similar  shipments  from  Europe,  and  for  the  first  time 
opportunity  was  afforded  for  the  actual  first-hand  investigation  of 
the  parasitic  fauna  of  the  gipsy  moth  in  Japan. 

Similar  shipments  were  made  in  1909  and  1910,  with  even  better 
results  in  so  far  as  the  condition  of  the  material  on  receipt  was  con- 
cerned, and  several  of  the  more  important  parasites  have  now  been 
liberated  in  the  held  in  America  under  conditions  which  are  appar- 
ently ideal  and  which  ought  to  encompass  their  introduction  and 
establishment,  if  such  a  thing  is  possible. 

Taui.k  I. — ^rrjucitcf  of  gipsy-moth  parasites  in  Japan. 


P4RAS/TES. 


EGG 


FRESH 

/o 

DAYS 


OLD 
280 
DAYS 


FIRST 

7 
DAYS 


L/1RV/1L  STAGES 


SEC- 
y 

DAYS 


TN/ftO  *OOHTf\  FtFTH  S.*Th 


7 

days 


7 

DAYS 


7 
DAYS 


7 
DAYS 


7 
DAYS 


PVP4L  SMGES 


2. 
DAYS 


FRESH  OLD 


3 
DAYS 


7 
DAYS 


AA/ASTATUS  &FXSC/AW5 
SCHED/US  KUVAA/AE 


APANTELES  FVCV/PES 

*UMA/EP/UM  D/SPAP/S 
*METEOPUS  JAFVA//CUS 
OfOSSOCOSM/A  SEPfCAR/Al 
TACP/A/A  JAPOA//CA 
*THEPOA//A  JAPOA//CA 
~*P/MPLA  PLUTO 
*P/MPLA  D/SPAP/S 
•kP/MPLA  POPTHETP/AE 
CHALC/S  OBSCUPATA 


FipST  $ENEP  IT/ON 


SECOND  genera;  10 h 


*  SPETC/SS  A/OT  COA/S/DEPED  TV  BE  Of  MUCH  /MPOPTAA/CE  ECOWOM/CJLLY. 


A  total  of  14  species  of  parasites  has  been  reared  from  the 
imported  material,  of  which  7  were  present  in  sufficient  abun- 
dance to  indicate  that  they  were  of  real  importance  in  effecting  the 
control  of  the  moth.  Two  species  are  of  such  doubtful  host  rela- 
tionship as  to  have  been  omitted  from  Table  1. 

Specimens  of  one  species,  M<  t<  <>tus  japonicus,  the  importance  of 
which  is  not  indicated  by  the  examination  of  the  imported  material, 
have  been  sent  to  us  by  Mr.  Kuwana  with  the  statement  that  it  is  some- 
times, locally  at  least,  a  common  parasite,  hut  none  for  colonization 
has  been  received.  Still  another  is  of  possihle  importance,  judging 
from  the  very  limited  opportunity  which  we  have  had  for  its  investi- 
gation, hut  none  of  the  others  is  of  proved  worth.  Since  nothing  is 
actually  known  of  the  conditions  under  which  particular  lots  of 


122  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

parasite  material  were  collected,  it  can  not  be  stated  as  confidently 
as  the  circumstances  render  desirable  that  some  among  the  others 
are  not  incidentally  of  value  in  keeping  reduced  the  numbers  of  the 
moth  in  localities  where  it  is  too  rare  to  permit  of  collection  of  mate- 
rial for  shipment  to  America. 

Prof.  Kinc aid's  reports  upon  the  effectiveness  of  the  parasites,  even 
when  taken  with  more  than  the  prescribed  grain  of  conservatism,  have 
been  so  consistently  optimistic  as  to  leave  no  room  to  doubt  that  the 
parasitism  to  which  the  moth  is  subjected  in  Japan,  even  in  localities 
where  it  is  more  than  normally  prevalent,  is  sufficient  to  meet  and 
overcome  the  rate  of  increase  of  the  gipsy  moth  in  America. 

How  these  parasites  work  together  in  bringing  about  the  control 
of  the  moth  in  Japan  is  indicated  in  Table  I,  which,  with  its  explana- 
tion, was  published  in  a  somewhat  abbreviated  form  in  the  popular 
bulletin  by  the  junior  author  which  was  issued  through  the  office  of 
the  State  forester  of  Massachusetts  a  year  ago. 

The  addition  of  the  names  of  the  species  marked  with  an  asterisk 
makes  the  list  complete,  so  far  as  it  may  be  completed  through  the 
information  now  available.  The  species  so  designated  are  those 
which  have  never  been  received  in  sufficient  abundance  to  make  their 
colonization  possible,  and  among  them  are  some  which  are  doubtless 
of  wholly  insignificant  importance  from  an  economic  standpoint, 
while  others  may,  upon  investigation,  prove  to  be  of  more  than  suffi- 
cient importance  to  justify  an  attempt  to  secure  their  introduction 
into  America. 

Opposite  the  name  of  each  parasite,  extending  across  a  certain 
number  of  the  vertical  columns,  is  a  dotted  line.  The  vertical  col- 
umns indicate  different  stages  in  the  development  and  transforma- 
tions of  the  gipsy  moth,  as  the  egg,  the  caterpillar,  and  the  pupa,  and 
these  are  still  further  divided  into  caterpillars  of  different  sizes  and 
eggs  and  pupas  of  different  ages  and  conditions.  At  the  head  of  eac  h 
column  is  stated  the  approximate  number  of  days  during  which  the 
individual  gipsy  moth  remains  in  that  particular  stage. 

The  dotted  line  following  the  name  of  the  parasite  indicates  those 
stages  in  the  life  of  the  gipsy  moth  during  winch  the  latter  is  likely 
to  be  attacked  by  the  parasite  in  question,  and  it  will  be  seen  that  in 
a  number  of  instances,  as,  for  example,  Chalcis  and  Theronia,  this 
period  is  exceedingly  short.  The  solid  line  indicates  the  stages  in  the 
life  of  the  gipsy  moth  during  which  it  is  likely  to  contain  the  parasite 
in  its  body.  This,  it  may  also  be  noted,  varies  considerably.  Crosso- 
cosmia,  for  example,  gains  lodgment  in  the  active  caterpillar  while 
it  is  only  about  half  grown,  and  the  extension  of  the  solid  line  across 
all  of  the  columns  which  stand  for  the  later  caterpillar  stages,  as  well 
as  for  all  of  the  pupal  stages,  indicates  that  tlx4  larvae  of  this  parasite 
do  not  leave  the  host  caterpillar  until  after  it  has  transformed  to  a 


EXTENT  OF  GTPSY-MOTH  PARASTTTSM  ABROAD. 


123 


pupa,  and  until  the  moth  would  naturally  have  emerged  had  the 
pupa  remained  healthy  and  unparasitized. 

It  will  be  noted  that  the  parasites  not  designated  by  the  asterisks, 
and  which  are  therefore  to  be  considered  as  of  some  importance  in 
effecting  the  control  of  the  moth,  form,  when  taken  together,  a  perfect 
sequence,  and  that  every  stage  of  the  moth  from  the  newly  deposued 
egg  to  the  pupa  is  subjected  to  attack.  It  is  furthermore  of  interest 
to  note  in  this  connection  that,  so  far  as  may  be  determined  from  the 
scanty  information  available,  all  of  these  parasites  are  present  in  more 
Of  less  efficient  abundance  within  a  limited  area  in  the  vicinity  of 
Tokyo,  from  which  a  part,  and  presumably  the  greater  part,  of  the 
material  was  collected  for  exportation. 

PAB  LSITISW   I  >F  THE  QIPS1    MOTE    I N    Rl  SSIA. 

The  earliest  first-hand  knowledge  of  the  gipsy  moth  and  its  para- 
sites in  Russia  was  secured  as  the  result  of  the  visit  paid  to  that 
country  by  the  senior  author  in  the  spring  of  1007.  Through  his 
instrumentality  several  of  the  Russian  entomologists  were  interested 
in  the  parasite-introduction  work  to  such  a  practical  extent  as  to 
collect  or  cause  to  he  collected  and  forwarded  to  America  several 
small  and  a  few  large  shipments  of  the  eggs,  caterpillars,  and  pupa4 
of  both  the  gipsy  moth  and  the  brown-tail  moth.     The  difficulties 

attending  the  importation  of  material  from  Russia  proved  to  be  con- 
siderably more  real  and  less  easily  surmount  able  than  those  which 

were  so  successfully  overcome  in  the  instance  of  the  Japanese  ship- 
ments, and  for  the  most  pari  the  Russian  material  was  of  more  interest 

from  a  technical  than  from  an  economic  standpoint  by  the  time  it 

arrived  at  the  laboratory. 

From  a  technical  standpoint  it  was  exceedingly  interesting  and 
valuable,  since  there  wore  found  to  be  present  in  the  boxes  of  young 
gipsy-moth  caterpillars  the  cocoons  of  several  species  of  hymenop- 
terous  parasites  which  had  either  not  been  received  from  other  sources 
or  which  were  Dot  known  to  be  sufficiently  abundant  in  any  other 
part  of  Europe  to  make  possible  their  collection  in  large  quantities. 
Prof.  Kincaid's  successful  prosecution  of  the  Japanese  work  encour- 
aged his  selection  as  the  best  and  most  experienced  agent  available 
for  the  decidedly  more  difficult  proposition  of  visiting  Russia  and 
attempting  to  secure  an  adequate  supply  of  the  several  species  of 
parasites  w  hich  could  only  be  secured  in  that  country  to  advantage, 
so  far  as  could  be  determined  from  the  information  then  at  hand. 

The  manner  in  which  he  was  impressed  by  the  gipsy-moth  situa- 
tion which  he  encountered  there  is  best  described  in  the  following 
extracts  from  his  Letters,  in  the  course  of  which  occasional  compari- 
sons are  made  between  Russian  and  Japanese  conditions. 


124  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

*  Bendery,  Bessarabia,  Russia,  June  11,  1909. 

The  season  here  is  in  full  swing,  but  the  situation  causes  me  considerable  anxiety, 
as  the  whole  business  is  so  utterly  different  from  my  experience  in  Japan.  The  dam- 
age wrought  by  dispar  in  the  forests  and  orchards  of  Bessarabia  this  season  is  enormous 
and  parasite  control  seems  to  be  most  inefficient  in  checking  the  depredations  of  the 
caterpillars.  When  I  think  of  the  masterly  and  well-ordered  attack  of  the  Japanese 
parasites  and  the  splendid  fashion  in  which  they  wiped  out  the  caterpillars  in  large 
areas  before  depredation  took  place  I  am  surprised  by  what  I  see  here.  When  I  left 
Gauchesty  on  May  31  the  forests  of  that  district  were  thoroughly  riddled  over  thousands 
of  acres,  and  yet  I  had  seen  no  sign  of  insects,  fungous,  or  bacterial  attack  except  a 
couple  of  clusters  of  Apanteles  cocoons.  *  *  *  Dispar  seemed  to  be  having  its 
own  way  as  fully  as  in  America,  so  far  as  could  be  seen  on  the  surface.  *  *  *  Here 
at  Bendery  the  season  is  slightly  more  advanced,  owing  to  the  lower  altitude,  and  the 
prospects  of  securing  parasites  of  dispar  seem  better.  Even  here,  however,  the  situa- 
tion seems  to  me  quite  remarkable.  I  have  available  three  extensive  and  very  dif- 
ferent collecting  grounds.  The  great  forest  of  Gerbofsky  about  6  versts  from  Ben- 
dery is  composed  almost  exclusively  of  oaks.  An  immense  area  is  covered  by  trees 
of  this  species,  forming  magnificent  groves  of  fine  trees  80  to  100  years  old.  Thousands 
of  these  great  trees  are  completely  defoliated,  so  that  no  sign  of  foliage  remains.  In 
the  same  forest  are  groves  of  young  trees  of  the  same  kind,  also  greatly  damaged. 
Examining  the  myriads  of  caterpillars  in  the  field,  I  have  found  no  sign  of  parasite 
attack  or  of  fungous  disease  except  the  work  of  Apanteles.  *  *  *  The  percentage 
of  attack  by  Apanteles  is  so  small  that  rearing  in  trays  is  of  little  practical  importance. 
One  would  have  to  have  billions  of  caterpillars  to  do  any  good.  Collecting  in  the 
field  is  very  difficult,  as  the  caterpillars  creep  into  crevices  or  suspend  themselves 
to  branches  at  some  height  from  the  ground,  where  they  are  hard  to  reach.  No  sign 
of  bacterial  disease  has  appeared  in  this  area,  nor  have  I  seen  any  evidence  of  tachinid 
attack  in  the  field  or  in  my  rearing  trays.  Another  great  forest  of  about  500  acres  is 
at  Kitzkany,  about  7  versts  from  Bendery  on  the  banks  of  the  Dniester,  a  low  damp 
situation.  This  forest  has  no  oaks  but  is  much  mixed.  The  principal  tree  is  Populus 
nigra,  but  there  are  many  other  trees,  as  Ulmus,  Acer,  Salix,  etc.  Here  again  the 
damage  is  tremendous,  with  almost  no  sign  of  parasite  attack.  Prolonged  search 
yielded  a  few  cocoons  of  Apanteles.  On  the  other  hand,  thousands  of  the  older  cater- 
pillars were  found  in  the  pendulous  condition  so  characteristic  of  bacterial  attack. 
The  third  condition  I  found  in  the  numerous  orchards  adjacent  to  both  of  these  for- 
ested areas.  These  orchards  have  been  almost  overwhelmed  by  dispar.  The  more 
progressive  peasants  have  protected  their  trees  by  rings  of  axle  grease  or  by  strips  of 
cotton  wool,  but  others  have  done  nothing  and  the  trees  are  quite  stripped.  *  *  * 
The  sight  of  a  tree  covered  with  hundreds  of  dead  caterpillars  bearing  clusters  of 
Apanteles  cocoons  such  as  I  saw  in  Japan  seems  not  to  be  hoped  for. 


Kief,  June  26,  1909. 
From  what  I  can  see  in  the  field  and  from  what  I  can  gather  from  Prof.  Pospielow, 
dispar  was  almost  exterminated  in  this  district  last  year  through  the  activity  of  the 
parasites.  Only  a  few  isolated  colonies  seem  to  have  survived,  the  most  important 
of  these  being  at  Mishighari,  a  small  place  on  the  river  about  two  hours  by  steamer 
from  Kief.  In  this  place,  which  is  perhaps  100  acres  in  extent,  the  tiees  are  plas- 
tered with  cocoons  of  Apanteles  fulvipes.  The  attack  of  the  parasite  was  so  thorough 
that  the  first  generation  seems  to  have  been  sufficient  to  wipe  out  the  caterpillars,  as 
I  can  find  no  large  Caterpillars  about  the  place,  and  a  few  days  will  doubtless  witrien 
the  complete  wiping  out  of  dispar.  *  *  *  Tachinids  also  appear  to  be  very  active, 
as  I  find  many  eggs,  bill  as  these  are  laid  upon  caterpillars  suffering  from  the  attacks 


EX  IT. X T  OF  GIPSY-MOTH    PARASITISM  ABROAD. 


125 


of  Apantelet  it  would  seem  as  if  the  emaciated  caterpillars  could  not  supply  sufficient 
nourishment  to  bring  the  tachinids  to  maturity.  *  *  *  From  the  standpoint  of 
parasite  control  the  situation  at  Kief  is  most  inspiring,  but  as  a  field  in  which  to  gather 
B  quantity  of  material  it  is  evidently  not  very  hopeful.  The  whole  situation  is  in 
violent  contrast  to  what  I  found  at  Bendery  and  (iauchesty,  when1  dispar  is  vastly 
more  abundant  this  year  than  last,  with  little  sign  of  the  multiplication  of  parasites. 


Bendery,  Russia,  July  10,  1909. 
In  the  fofest  of  Kitzkany  where  dispar  caterpillars  prevailed  to  an  incredible  extent 
three  weeks  ago,  not  a  single  caterpillar  or  pupa  is  to  be  found.  An  epidemic  of  a 
bacterial  nature  swept  them  away  in  millions.  In  the  forest  of  (lerbofsky,  among 
the  great  oak  trees,  the  number  of  caterpillars  that  have  formed  pupae  is  surprisingly 
small.  Vast  numbers  of  caterpillars  swarmed  over  the  trees,  completely  stripping 
them  of  leaves.  Deserting  the  trees,  the  caterpillars  swarmed  over  the  ground  in 
search  of  other  food  and  vast  numbers  died  of  starvation  and  disease.  These  trees 
arc  now  putting  forth  new  leaves  which  promise  to  sustain  the  life  of  the  forest. 

After  the  (dose  of  the  ''caterpillar  season  "  in  1  * » 1  ( )  the  junior  author 
took  a  vacation  trip  to  Knrope  and,  thanks  to  an  extension  of  leave 
for  the  purpose  and  still  more  to  the  kindness  of  Mr.  N.  Kourdumoff, 
entomologist  of  the  experiment  station  in  Poltava,  was  enabled  to 
spend  about  10  clays  in  the  field  in  Kief  and  Kharkof  Provinces.  In 
Kief  the  forest  at  Mishighari,  which  is  mentioned  by  Prof.  Kincaid 
as  the  one  locality  where  lie  found  the  parasites  in  control,  was  visited, 
as  well  as  several  other  localities  in  that  province.  This  portion  of 
Kief  Province,  topographically,  meteorologically,  and  otherwise,  is 
radically  different  from  Massachusetts,  and  much  more  like  portions 
of  Minnesota  than  any  other  part  of  the  United  States  w  ith  which  the 
visitor  is  at  all  familiar.  The  forests,  which  are  limited  in  extent  as 
compared  with  those  of  Massachusetts,  are  less  diversified.  For 
the  most  part  they  are  of  pine,  mingled  with  a  small  quantity  of  oak, 
wild  pear,  birch,  and  occasionally  other  trees.  Everywhere  the 
gipsy  moth  was  rare  or  at  least  uncommon,  and  everywhere  the 
cocoon  masses  of  ApanUhs  fvlvipes  were  at  least  as  abundant  as  the 
egg  masses  of  their  host. 

At  Mishighari  the  conditions  remained  much  as  described  by  Prof. 
Kincaid,  except  that  the  cocoon  masses  of  Apanteles  were  even  moro 
abundant  than  lus  letters  would  indicate.  Upon  SOme  trees  they 
were  litterally  matted  together  by  the  thousands  in  such  semipro- 
tected  situations  as  are  selected  by  the  caterpillars  at  the  time  of 
molting.  The  forest  in  this  part  icular  locality  w  as  varied  to  an  extent 
not  noticed  elsewhere.  In  addition  to  the  generally  distributed  oak, 
birch,  and  poplar  were  quantities  of  beech,  Jder,  Carpinus,  maple, 
elm,  and  other  species,  while  the  shrubs  were  equally  varied  and  abun- 
dant. The  forest  was  situated  upon  the  steep  bluffs  overhanging  the 
Dnieper,  running  down  on  one  side  to  its  banks,  where  great  wallows 
bore  evidence  of  the  high  wrater  which  sometimes  covered  their 


126  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

trunks,  and 'on  the  other  extending  back  some  little  distance  until  it 
was  met  by  a  wide  stretch  of  treeless  prairie.  Here,  at  least,  parasite 
control  of  the  gipsy  moth  appeared  to  be  pretty  thoroughly  effective, 
since  there  were  in  evidence  a  vastly  larger  number  of  old  cocoon 
masses  of  the  Apanteles  than  there  were  of  old  egg  masses  of  its  host, 
and  the  new  egg  masses  were  enormously  outnumbered  by  the  old. 
According  to  Prof.  Pospielow,  who  was  a  member  of  the  party,  the 
forest  in  this  locality  was  almost  completely  defoliated  in  1908,  but 
there  was  no  indication  of  damage  to  any  of  the  trees  composing  it, 
and  every  indication  that  the  parasites  alone  were  responsible  for  the 
disappearance  of  the  moth. 

In  several  other  localities  along  the  banks  of  the  Dnieper  the  condi- 
tions encountered  were  essentially  the  same,  differing  principally  in 
the  lesser  abundance  of  both  egg  masses  and  parasite  cocoons.  In 
one  locality  quite  near  to  Kief,  fresh  egg  masses  were  more  common 
than  at  Mishighari,  and  cocoon  masses  of  the  season  of  1910  were  also 
more  common.  It  seemed  to  offer  opportunities  for  the  collection  of 
a  sufficiently  large  quantity  of  this  parasite  to  make  an  experiment  in 
importation  and  colonization  possible  and  practicable  in  1911,  which 
it  is  hoped  may  be  carried  out. 

In  Kharkof  conditions,  both  as  regards  the  gipsy  moth,  its  para- 
sites, and  the  country  at  large,  were  essentially  different  from  those 
in  Kief.  Numerous  localities  from  5  to  20  miles  out  of  the  city  in 
different  directions  were  visited,  and  everywhere  indications  of  the 
recent  presence  of  the  gipsy  moth  were  found  in  abundance.  Old  egg 
masses  were  massed  around  the  base  of  the  trees  in  a  manner  exceed- 
ingly suggestive  of  uncared  for  woodland  in  Massachusetts,  and 
mingled  with  them  were  a  very  few  fresh  masses;  so  few,  relatively, 
as  to  indicate  most  conclusively  that  the  moth  had  encountered  very 
adverse  conditions  during  the  season  of  1910,  with  the  result  that  its 
abundance  had  been  most  materially  reduced. 

In  every  locality  the  conditions  were  the  same,  although  the 
character  of  the  forest  varied  to  a  material  extent.  For  the  most  part 
.the  province  of  Kharkof  is  devoid  of  forest,  and  quite  suggestive  of 
parts  of  North  Dakota  in  appearance.  Such  forest  as  does  occur  is 
mostly  confined  to  the  valleys  in  the  neighborhood  of  streams,  and 
though  it  may  be  fairly  extensive,  it  is  rarely  very  diverse.  No  pine 
was  seen.  Oak  predominates  very  largely  and,  with  the  exception 
of  some  birch,  forms  practically  pure  forests  away  from  the  lowlands, 
except  in  the  best  watered  localities. 

K  very  where,  irrespective  of  the  character  of  the  forest,  the  gipsy 
moth  was  found  under  the  circumstances  recounted  above.  Every- 
where there  had  been  an  abundance  of  eggs  in  the  spring,  everywhere 
there  had  been  an  abundance  of  caterpillars,  a  considerable  propor- 


EXTENT  OF  GIPSY-MOTH  PARASITISM  ABROAD. 


127 


tion  of  which  had  gone  through  to  pupation,  and  everywhere  the 
Dumber  of  fresh  egg  masses  was  very  much  smaller  than  was  that  of 
the  okl.  Nowhere  was  there  evidence  of  parasitism  by  Apanteles 
fulvipes  to  anything  like  the  extent  which  prevailed  in  the  vicinity  of 
Kief.  Cocoon  masses  were  occasionally  found,  nearly  always  old, 
sometimes  ver)  old  and  so  discolored  as  to  be  with  difficulty  dis- 
tinguished from  the  hark  to  which  they  were  attached.  In  Kief  the 
number  of  cocoon  masses  was  everywhere  in  considerable  excess  over 
the  number  ol  egg  masses.  Here  the  nnmher  of  egg  masses  was  enor- 
monslv  in  excess  of  the  number  of  cocoon  masses. 

Kxamination  of  the  pupal  shells  for  evidences  of  parasitism  was 
unavailing.  It  could  be  said  with  assurance  that  pupal  parasites 
wen'  certainly  not  common  and  that  the  death  of  the  pupa'  (for  pro- 
portionately very  few  of  them  hatched)  was  not  due  to  any  of  the 
pupal  parasites  which  were  known  from  western  European  localities. 
The  earth  beneath  the  cocoon  masses  was  examined  for  evidences  of 
tachinid  puparia.  For  a  time  none  was  found,  but  search  w  as  finally 
rewarded  by  t he  discovery  of  Blepharijxi  scutdhita  in  most  extraor- 
dinary abundance  in  a  single  one  among  the  numerous  localities 
visited.  This  particular  forest,  which  was  very  near  to  the  village 
of  Khijhof  and  about  S  miles  from  Kharkof,  was  unique  among  the 
others  visited  in  the  variety  of  its  trees.  The  soil  was  rich,  the  trees 
were  larger,  and  the  undergrowth  was  more  abundant  and  varied, 
but  at  the  same  time  there  was  less  diversity  than  was  encountered 
in  the  forest  at  Mishighari.  I'nfort  unately,  the  presence  of  the 
puparia  could  not  be  considered  as  of  much  significance,  because  they 
were  practically  all  hatched  and  obviously  dated  back  more  than  one 
year.  The  parasite  had  surely  not  been  responsible  for  the  reduction 
in  numbers  of  the  gipsy  moth  which  had  taken  place  in  the  season  of 
1910,  and  neither  had  it  prevented  the  moth  from  increasing  to  such 
numbers  as  to  bring  about  partial  defoliation  of  the  forest  in  1910 
before  disaster  in  one  form  or  another  bad  overtaken  it. 

Of  other  tachinids  there  were  practically  none,  and  it  is  certain  that 
they  would  have  been  found  had  they  been  present.  Compsilura 
concinnata  is  even  now  so  abundant  as  a  parasite  of  the  gipsy  moth  in 
Massachusetts  as  to  bring  about  an  appreciable  percentage  of  des1  ruc- 
tion in  1910,  and  its  puparia  are  recovered  from  tin4  field  with  ease. 
Had  it  been  one-tenth  as  common  in  Russia  it  could  not  have  failed 
of  detection.  The  same  is  true  of  Tachma,  which,  although  it  effects 
a  parasitism  of  less  than  1  percent  in  Massachusetts,  is  not  diflicult 
of  detection,  and  it  is  safe  to  say  that  not  much  if  any  more  than  this 
amount  of  parasitism  prevailed  in  Kharkof.  All  told,  not  enough 
parasites  were  found  to  indicate  that  they  had  played  any  important 
part  in  the  reduction  of  the  moth  from  a  serious  menace  to  the  well- 


128 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


being  of  the  forest  to  such  small  numbers  as  to  require  several  years 
at  least  before  it  would  be  possible  for  such  conditions  to  recur. 

The  investigations  having  been  conducted  in  September,  some  time 
after  the  death  of  all  of  the  caterpillars  and  pupae,  it  was  no  longer 
possible  to  determine  with  assurance  the  cause  for  the  peculiar  condi- 
tions, but  everything  conspired  to  indicate  .that  nothing  less  than  an 
epidemic  of  disease  had  been  responsible.  The  condition*  of  the 
pupal  shells  which  hung  upon  the  trees  in  countless  thousands  was  in 
every  respect  identical  with  the  condition  of  the  pupal  shells  which 
are  to  be  found  in  Massachusetts  in  every  locality  where  the  disease 
has  prevailed  to  a  destructive  extent  the  season  before.  Among  the 
old  egg  masses  which  plastered  the  extreme  base  of  nearly  every  tree 
in  most  of  the  localities  visited  were  found  a  variable,  and  sometimes 
a  very  large,  proportion  which  had  hatched  only  in  part  or  not  at  all. 
The  appearance  of  these  unhatched  masses  was  identical  in  every 
respect  with  the  appearance  of  similarly  large  numbers  which  are 
frequently  found  in  Massachusetts.  The  reason  for  the  nonhatching 
of  the  eggs  is  not  yet  plain,  but  it  is  the  consensus  of  opinion  that  this 
is  probably  associated  with  the  "wilt"  disease.  It  is  known  that 
affected  caterpillars  may  pupate  before  death,  and  it  seems  not  illogi- 
cal to  suppose  that  slightly  affected  caterpillars  may  pupate  and 
produce  moths  which  are  able  to  deposit  their  eggs,  but  that  these 
eggs  fail  to  hatch  as  the  direct  result  of  the  taint  in  the  blood  of 
their  parent. 

These  Russian  experiences  seem,  on  the  whole,  to  indicate  that 
in  that  country  the  gipsy  moth  is  not  controlled  by  its  parasites  to 
an  extent  which  serves  to  remove  it  from  the  ranks  of  a  destructive 
pest.  But  as  one  day  after  another  in  the  field  at  Kharkof  served 
more  and  more  indelibly  to  deepen  this  conviction,  it  served  equally, 
first  to  create,  and  finally  in  retrospect  to  confirm,  the  observer  in 
another,  which  was,  in  effect,  that  if  this  was  the  best  that  could  be 
expected  of  disease  as  a  factor  in  the  control  of  the  gipsy  moth  in  its 
native  home  then  something  better  than  disease  must  be  found  to 
control  it  in  America.  Just  so  long  as  conditions  similar  to  those  seen 
in  Kharkof  or  pictured  in  the  letters  of  Prof.  Kincaid  are  allowed  to 
prevail  in  Massachusetts  just  so  long  will  the  incentive  remain  to  see 
the  parasite-introduction  experiment  carried  on  until  success  is  either 
achieved  or  proved  impossible.  Conditions  similar  to  those  prevail- 
ing in  Russia  emphatically  do  not  prevail  in  western  Europe,  nor, 
according  to  all  accounts,  in  Japan.  Natural  conditions  in  western 
Europe  and  in  Japan  are  in  many  respects  more  like  those  of  our  own 
Eastern  States  than  are  those  of  Kharkof  Province.  Conditions  in 
Kief  Province,  even,  are  much  more  like  those  of  Massachusetts  than 
are  those  of  Kharkof,  and  in  Kief  parasite  control  seemed  to  be  an 


EXTENT  OF  GIPSY-MOTH  PARASITISM  ABROAD. 


129 


accomplished  fact,  although  of  course  there  is  no  assurance  that  it  is 
continuous  and  perfect. 

The  final  outcome  of  the  Russian  experience  was,  therefore,  the 
opposite  of  what  might  have  been  expected,  and  it  resulted  in  a  firmer 
determination  than  ever  to  carry  the  work  through  to  its  end. 

EfeRASITISM  OF  THE  GD?SI   MOTH   IN   SOUTHERN  FRANCE. 

Following  the  10  days  in  Russia  a  shorter  period  was  spent  by  the 
junior  author  in  somewhat  similar  field  work  in  southern  France, 
where,  with  the  aid  of  M.  Dillon,  he  was  enabled  to  visit  the  localities 
from  which  the  largest,  and  in  that  respect  the  most  satisfactory, 
shipments  of  parasite  material  ever  received  at  the  laboratory  were 
collected.  As  the  direct  result  of  the  senior  author's  visit  to  Europe 
in  1009  some  thousands  of  boxes  containing  hundreds  of  thousands  of 
gipsy-moth  caterpillars  had  been  collected  in  the  vicinity  of  llyeres, 
about  50  miles  to  the  eastward  of  Marseilles.  These  caterpillars  were 
largely  living  upon  receipt,  and  in  the  winter  of  1909-10  Mr.  W.  B. 
Thompson  dissected  several  hundred  preserved  specimens  and  the 
actual  percent  age  of  parasit  ism  was  t  bus  (let  erinined.  Some  few  pupa3 
which  had  also  been  received  from  the  same  locality  made  possible  a 
fair  undersl  anding  of  the  extent  to  which  the  pups  ^  ere  parasitized. 

The  results  of  these  investigations,  taken  in  connection  with  the 
actual  rearing  work,  were  disappointing.  It  was  evident  that  the 
moth  was  fairly  common  in  t  he  legion  from  which  the  material  was 
collected — as  common,  perhaps,  as  it  would  need  to  be  in  Massachu- 
setts to  provide  for  an  increase  of  sixfold  annually.  Nevertheless, 
the  amount  of  parasitism  which  was  indicated  by  this,  the  most 
thorough  study  of  parasitism  of  the  gipsy  moth  abroad  which  was 
ever  undertaken  in  the  laboratory,  was  less  than  enough  to  offset  a 
twofold,  much  less  a  sixfold,  increase. 

For  this  reason  much  curiosity  was  felt  as  to  the  conditions  wJiich 
prevailed  in  a  country  where  parasitism  of  such  comparatively  insig- 
nificant proportions  w  as  sufficient. 

Nose  oner  was  the  character  of  the  country  districts  in  this  portion 
of  France  seen  than  the  wonder  which  had  been  felt  at  the  small  per- 
centage of  parasitism  which  w  its  sufficient  to  hold  it  in  check  w  as 
replaced  by  a  much  greater  astonishment  that  the  gipsy  moth  should 
exist  under  such  conditions  at  all.  It  w  as  a  country  of  olive  orchards 
and  vineyards,  with  a  strip  along  the  littoral  which  was  so  nearly 
frostless  as  to  permit  the  culture  of  citrus  fruits,  and  even  of  date 
palms.  The  hills  were  semiarid,  with  the  soil  exceedingly  scanty  and 
often  covered  by  loose  stones.  The  principal  forests  consisted  largely 
of  cork  oak  and  pine,  except  in  the  low  and  w  ell-w  atered  valleys  and 
bottom  lands  where  other  trees  in  considerable  variety  occurred. 
95077°— Hull.  91—11  9 


130 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


The  slopes  of  the  higher  mountains  were  fairly  well  forested  and  a 
larger  variety  of  trees  and  shrubs  thrived  than  on  the  lower  elevations. 
Over  much  of  the  country  the  soil  was  either  too  dry  or  too  scanty  or 
both  to  permit  of  cultivation,  even  in  a  land  so  densely  populated  by  so 
thrifty  a  race,  and  here  were  found  occasional  thickets  of  scrub  oak, 
apparently  of  a  deciduous  species,  which  sometimes  reached  the 
dignity  of  a  small  tree.  For  the  most  part  such  country  was  covered 
with  a  scanty  growth  which  would  be  called  chapparal  in  some  of  our 
States,  composed  of  a  variety  of  uninviting  looking  shrubs,  judging 
them  from  the  probable  viewpoint  of  a  gipsy-moth  caterpillar  in 
search  of  food.  Taken  altogether,  the  country  may  more  aptly  be 
compared  with  southern  California  than  with,  any  other  part  of  the 
United  States. 

It  seemed  to  the  visitor  that  if  the  gipsy  moth  were  to  be  found  in 
any  portion  of  this  region  it  would  most  likely  be  within  the  rich  and 
well-watered  bottom  lands,  where  occasional  hedges,  or  rows  and 
groups  of  large  trees  in  considerable  variety,  seemed  to  offer  fairly 
acceptable  conditions  for  its  existence.  But  to  his  surprise  and 
amazement  he  was  assured  by  M.  Dillon  that  it  was  from  the  chapparal 
covered,  arid,  and  uncultivated  elevations  that  most  of  the  enormous 
quantities  of  caterpillars  had  been  collected.  In  support  of  this  asser- 
tion, after  the  visitor  had  searched  in  vain  in  what  would  be  the  most 
likely  situations  in  Massachusetts  for  the  concealment  of  egg  masses, 
pupal  shells,  or  molted  skins,  M.  Dillon  proceeded  to  turn  over  a  few 
loose  stones  among  those  which  fairly  covered  the  ground,  and  thereby 
disclosed  sufficient  indication  of  the  presence  of  the  moth  in  fair 
abundance  to  convince  the  most  skeptical.  In  this  particular 
locality  in  the  vicinity  of  the  little  provencal  town  of  Meoun,  in  a 
thicket  of  deciduous  oak  surrounding  and  concealing  the  ruins  of  an 
ancient  chapel,  there  were  sufficient  egg  masses  of  the  moth  to  repre- 
sent a  fair  degree  of  infestation,  but  eggs,  pupal  shells,  and  molted 
larval  skins  were  all  so  completely  hidden  as  to  evade  completely  the 
eyes  of  one  who  had  been  trained  to  look  for  first  evidences  in  shel- 
tered places  on  the  bark  or  in  the  knot  holes  and  hollow  trunks  of 
trees. 

As  a  .matter  of  fact,  as  was  abundantly  evidenced  by  that  day's 
experiences,  as  well  as  of  the  several  days  which  followed,  the  gipsy 
moth  departed  most  materially  from  its  characteristic  habits  in  the 
cooler,  better  watered  and  forested  localities  in  which  it  is  present  as  a 
pest  in  America.  Instead  of  being  a  typically  arboreal  insect,  it  is 
rather  terrestrial,  and  thereby  becomes  subjected  to  a  variety  of  nat- 
ural enemies  to  which  it  is  practically  immune  so  long  as  it  remains 
arboreal,  In  the  course  of  the  several  years  past  a  variety  of  species 
of  the  larger  European  Carabidas  has  been  studied  at  the  laboratory 
for  the  purpose  of  determining  their  availability  and  probable  worth 


SEQUENCE  OF  GIPSY-MOTH  PARASITES  IX  EUROPE. 


131 


as  enemies  of  the  gipsy  moth.  Of  them  all,  not  one  refused  to  attack 
and  devour  the  caterpillars  and  pupae  of  the  gipsy  moth  with  business- 
like dispatch,  once  given  an  opportunity,  but  with  one  or  two  excep- 
tions none  has  shown  a  disposition  to  climb  trees  in  search  of  its  prey. 
Being  essentially  terrestrial  in  habit,  they  were  essentially  unfitted 
to  prey.upon  an  essentially  arboreal  insect. 

We  know  little  of  the  predatory  beetles  which  are  to  be  found  in 
that  part  of  France  which  was  visited  Upon  this  occasion,  nor  does 
this  lack  of  knowledge  vitiate  the  strength  of  the  argument  to  any 
greal  extent.  The  fact  was  that  if  present  (and  undoubtedly  some 
species  are  to  be  found)  any  of  the  numerous  forms  which  have  been 
studied  at  the  laboratory  and  discarded  as  unlit  for  the  purposes  de- 
sired in  Massachusetts  would  immediately  assume  high  rank  as  ene- 
mies of  the  gipsy  moth.  In  other  words,  the  conditions  under  which 
the  gipsy  moth  exists  in  southern  France  are  wholly  incomparable  with 
those  under  which  it  exists  in  New  Kngland,  and  the  agencies  which 
are  effective  in  accomplishing  its  control  are  Likewise  incomparable. 
The  unimportant  role  obviously  played  by  the  parasites  immediately 

loses  its  significance.  Those  species  of  true  parasites  which  assist  in 
this  control  are  practically  the  same  as  those  which  assist  in  other 
localities,  but  the  demand  upon  them  and  their  opportunities  for  mul- 
tiplication are  insignificant  compared  to  those  existing  in  Massachu- 
setts, if  they  are  ever  established  there.  True  to  their  character  as 
agencies  in  facultai  ive  cont  rol,  i  hey  do  not  increase  in  efficiency  to  an 

extent  which  would  practically  mean  the  extinction  of  their  host. 

The  results  of  the  rearing  and  dissection  work  carried  on  at  the 
laboratory  indicated  thai  a  parasitism  varying  from  25  per  cent  to 
something  in  excess  of  40  per  cent  prevailed  in  this  locality.  After 
seeing  the  conditions  under  which  the  gipsy  moth  struggled  for  ex- 
istence, real  wonder  was  fell  that  it  should  be  able  to  survive,  and  the 
trip  resulted  in  a  I  inner  conviction  than  ever  in  the  eflicacy  of  para- 
sitism, and  the  validity  of  the  theory  upon  which  the  parasite-intro- 
duction work  w  as  conceived. 

SEQUENCE  OF  PARASITES  OF  THE  GIPSY  MOTH  IN  EUROPE. 

The  parasitic  fauna  of  the  gipsy  moth  varies  considerably  in  various 
faunal  divisions  of  Kurope,  and  no  attempt  has  been  made  to  prepare 
separate  lists  of  tin4  parasites  peculiar  to  those  regions  which  have 
been  represented  in  the  material  imported.  In  Table  II,  which  is  con- 
structed in  accordance  with  that  representing  the  sequence  of  para- 
sites in  Japan,  as  explained  on  page  122,  all  of  the  various  species  reared 
from  the  European  material  are  listed.  As  in  the  table  of  Japanese 
parasites  those  species  which  are  of  no  consequence  in  the  control  of 
the  moth  (so  far  as  known)  are  marked  with  an  asterisk. 


132 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


THE  BROWN-TAIL  MOTH  AND  ITS  PARASITES  IN  EUROPE. 

Reference  has  already  been  made  to  the  fact  that  in  those  sections 
of  Massachusetts  in  which  both  the  gipsy  moth  and  the  brown-tail 
moth  occur,  the  latter  is  considered  as  the  lesser  pest  of  the  two. 
This  opinion,  as  held  by  those  who  are  thoroughly  familiar  with  the 
comparative  noxiousness  of  the  two,  speaks  quite  plainly  of  the  char- 
acter of  the  gipsy  moth  as  a  pest,  in  view  of  the  very  considerable  agi- 
tation which  has  come  about  on  account  of  the  brown-tail  moth  in 

Table  II. — Sequence  of  gipsy-moth  parasites  in  Europe. 


fXR/IS/TES. 


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S/XTH 

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localities  into  which  it  has  preceded  the  gipsy  moth  or  where  the  latter 
has  not  as  yet  reached  a  state  of  destructive  abundance. 

On  account  of  the  lesser  interest  aroused  in  the  brown-tail  moth  in 
Massachusetts,  its  parasites  have  not  been  given  quite  the  considera- 
i  ion,  in  some  respects,  that  has  been  given  to  those  of  the  gipsy  moth, 
but  this  lack  of  consideral  ion  has  bad  entirely  to  do  with  the  question 
of  the  future  policy  of  the  laboratory,  and  has  not  extended  to  the 
actual  handling  of  Hie  parasites  themselves.  In  every  respect  other 
than  as  a  basis  lor  calculations  as  to  future  policies  of  the  labora- 


BROWX-TAIL  MOTH  AND  PARASITES  TX  EUROPE. 


133 


torv.  they  have  received  as  much  and  as  careful  consideration  as 
have  the  parasites  of  the  more  dangerous  pests. 

So  far  as  known  the  brown-tail  moth  does  not  occur  in  Japan,  and 
in  consequence  no  determined  efforts  have  been  made  to  secure, from 
Japanese  sources,  parasites  likely  to  attack  it.  It  has  an  ally  and  con- 
vener there  in  Euproctis  conspersa  Butl..  which  is  attacked  by  a  variety 
of  parasites,  some  of  which  may  be  expected  to  attack  the  brown-tail 
moth  if  given  an  opportunity.  A  few  of  them  have  been  collected 
and  forwarded  to  the  Laboratory  through  the  great  kindness  of  Mr. 
Kuwana.  but  unfortunately  have  arrived  in  such  condition,  or  at  such 
time  of  the  year,  as  to  make  their  colonization  impossible.  It  is 
intended  in  the  near  if  not  in  the  immediate  future  to  devote  some 
time  to  the  investigation  of  the  Japanese  parasites  likely  to  be  of 
service  in  this  respect ,  and.  if  any  can  be  found  of  promise,  to  attempt 
their  importation  into  America. 

In  Kurope  the  brown-tail  moth  appeals  to  be  the  more  common  of 
the  t  wo  insects  under  considerat  ion  and.  t  aken  all  in  all,  it  is  probably 
the  more  injurious  as  well.  Neither  in  Europe  nor  in  America  does 
it  bring  about  the  wholesale  defoliation  characteristic  of  an  invasion 
of  the  gipsy  moth,  but  its  injury  is  of  a  more  insidious  character  and 
more  evenly  distributed  throughout  the  years.  In  Russia,  in  the  fall 
of  i«jio.  the  junior  anthoi  was  astounded  at  the  tremendous  abun- 
dance of  its  nests  in  many  localities,  notably  on  the  irregular  hedge- 
row^ planted  as  a  windbreak  alongside  the  railroad  in  the  midst  of  an 
otherwise  open  prairie.  Occasionally  small  scrubs  of  Crataegus,  or 
wild  pear,  completely  isolated  by  what  seemed  to  be  miles  of  open 
prairie,  would  be  fairly  covered  with  the  nests. 

In  gardens  in  the  vicinity  of  Kief  pear  and  apple  trees  were  fre- 
quently injured  to  a  considerable  extent  by  its  caterpillars,  and  some- 
times to  a  greater  extent  by  the  caterpillars  of  Aporia  cratsegi  L., 
which  are  similar  in  their  habit .  and  were  constructing  their  own  hiber- 
nating ne>ts  side  by  side  with  those  of  the  brown-tail  moth.  In  the 
forests  round  about  it  was  common,  but  except  on  asionally  not  quite 
so  common  as  in  southeastern  New  England.  On  one  occasion  in 
excess  of  50  nests  were  noted  upon  a  small  hawthorn  which  stood  at 
the  edge  of  an  oak  forest.  This  was  just  a  little  worse  than  anything 
which  has  been  seen  in  America. 

In  southern  Prance  the  circumstances  under  which  it  occurred  were 
as  surprising  as  those  under  which  the  gipsy  motb  w  as  encountered, 
in  respect  to  their  departure  from  that  which  past  experience  led  the 
visitor  to  consider  as  the  normal.  M.  Dillon,  who  had  collected  and 
forwarded  to  the  laboratory  a  considerable  quantity  of  the  winter 
nests,  undertook  to  guide  the  visitor  to  the  locality  where  they  were 
collected.  The  way  led  through  a  rich  and  fertile  valley,  with  many 
sorts  of  trees,  including  apple  and  pear,  as  well  as  hawthorn  and  oak, 


134 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


every  one  of  which  is  a  favored  host  plant  in  other  regions,  but  not  a 
single  brown-tail  nest  was  seen  and,  according  to  M.  Dillon,  it  was 
never  found  upon  these  trees.  Farther  on  an  elevated  plain  was 
passed,  with  occasional  ridges  of  uncultivated  land  upon  which  were 
growths  of  a  deciduous  scrub  oak.  Gipsy-moth  eggs,  pupal  shells, 
etc.,  could  usually  be  found  by  a  little  search  under  the  stones  on  these 
ridges,  but  the  brown-tail  moth  was  conspicuous  by  its  total  absence. 

The  next  da}^  the  route  selected  passed  through  an  extensive  forest 
of  cork  oak,  mingled  with  pine,  and  finally  up  the  sides  of  the  moun- 
tain, until  great  plantations  of  aged  chestnut  trees  were  indicative  of  a 
change  in  climatic  conditions  brought  about  by  the  considerable  alti- 
tude. Various  shrubs  and  a  few  trees  unknown  or  rare  in  the  lower 
elevations  became  a  feature  of  the  forest,  and  among  them  the  arbusier 
(Arbutus  sp.),  closely  resembling  in  its  growth,  in  the  appearance  of  its 
evergreen  foliage,  and  in  its  habitat  the  mountain  laurel  of  our  own 
southern  mountains.  It  is  very  beautiful  and  unusual  in  its  appear- 
ance, partly  on  account  of  its  flowers  (which  are  suggestive  of  Oxy- 
dendron)  but  more  particularly  because  of  its  fruit.  This  was  globu- 
lar, about  the  size  of  a  marble,  and  hung  pendant  on  long  stems  in 
more  or  less  profusion,  and  in  all  stages  of  ripening.  In  the  course  of 
this  process  it  passed  from  green  through  a  sequence  of  vivid  yellows 
to  orange,  and  finally  intense  scarlet.  It  was  at  once  recognized  as 
the  host  plant  of  the  hundreds  of  nests  which  had  been  collected  and 
shipped  by  M.  Dillon.  Although  it  was  occasionally  met  with,  suffi- 
ciently far  down  the  mountain  side  to  mingle  with  orchards  and 
hawthorn  hedges,  according  to  M.  Dillon  the  brown-tail  moth  invari- 
ably seeks  it  out,  even  there.  The  selection  of  a  food  plant  repre- 
senting a  totally  different  order  from  any  selected  in  other  parts  of 
Europe  or  in  America,  and  this  in  spite  of  the  fact  that  what  are 
ordinarily  its  most  favored  hosts  were  frequently  much  the  more 
abundant,  was  considered  to  be  quite  as  remarkable  as  the  assump- 
tion of  terrestrial  habits  by  the  gipsy  moth.1 

In  central  and  western  Europe  generally  the  brown-tail  moth  finds 
a  stronghold  in  the  dense  Crataegus  hedges  which  are  commonly 
planted  in  many  localities,  and  upon  them  as  well  as  upon  oak  and 
fruit  t  rees  it  is  frequently  abundant.  In  these  regions,  also,  not  only 
the  food  plants,  but  the  seasonal  and  feeding  habits  are  quite  like 
those  in  New  England.  Occasionally  an  apple  tree  or  an  oak  will  be 
found  carrying  an  abundance  of  nests  and,  as  noted  by  the  senior 
author  in  northwestern  France  in  1901),  the  moths  are  sometimes  so 

'  II  has  since  been  Learned  that  in  the  warmer  parts  of  the  region  visited,  the  brown-tail  moth  caterpillars 
not  only  remain  active  but  feed  to  some  extent  during  the  winter.  In  the  middle  of  January,  1911,  the 
nests  were  found  commonly,  always  upon  Arbutus,  in  parts  of  the  coast  regions  near  Hyeres,  and  in  nearly 
every  instance  the  caterpillars  were  active  and  in  most  they  were  feeding.  In  this  particular  locality  the 
nests  were  very  different  from  those  typical  of  the  caterpillars  in  northern  localities,  being  loosely  woven, 
and  not  at  all  designed  for  hibernation  in  its  stricter  sense. 


BROWX-TAIL,  MOTH  AND  PARASTTES  TX  EUROPE. 


135 


numerous  as  to  lay  their  eggs  in  quantities  on  growing  nursery  seed- 
lings and  low-growing  plants. 

Among  the  very  many  lots  01  caterpillars  and  cocoons  which  have 
been  received  at  the  laboratory  there  is  occasionally  one  in  which  a 
fungous  disease  is  present.  Usually,  when  it  is  present  at  all,  the 
majority  of  the  caterpillars  received  from  that  particular  locality 
will  be  found  dead  and  " shooting1 '  the  ascidiospores  upon  receipt. 
According  to  Dr.  Roland  Thaxter.  to  whom  specimens  have  several 
times  been  submitted,  it  is  specifically  identical  with  the  fungus 
which  is  so  effective  in  America  as  to  have  largely  assisted  in  reduc- 
ing the  moth  from  the  preeminent  place  which  it  woidd  otherwise 
have  occupied  as  a  pest.  Its  presence  under  these  conditions,  as  it 
was,  for  example,  in  1  !)()(>,  in  practically  every  box  out  of  a  large 
number  which  were  forwarded  to  the  laboratory  from  lower  Austria, 
is  strongly  indicative  of  the  importance  of  this  disease. 

Looked  at  from  one  standpoint,  the  brown-tail  moth  situation  in 
America  is  less  satisfactory  than  is  the  gipsy-motb  situation.  In 
numerous  localities  throughout  western  Kuropc  as  well  as  in  eastern 
Europe  it  frequently  increases  to  such  an  extent  as  to  become  a 
pest.  It  hardly  seems  as  though  more  could  be  expected  of  the 
European  parasites  in  America  ihan  is  accomplished  by  them  in 
Europe,  but  if  even  this  much  can  be  secured  it  will  aid  materially 
in  reducing  I  he  frequency  <>f  t  he  out  breaks.     At  t  lie  same  t  hue,  it  must 

be  admitted  that  from  Dearly  every  point  of  view  the  prospects  of 
unqualified  success  with  the  gipsy-moth  parasites  are  better  than 

with  the  parasites  of  the  brown-tail  tnoth. 

BEQUBNCE   OF    PARASITES   OF    I'm:    BROWN-TAIL    MOTH    IX  EUROPE. 

The  accompanying  table  (Table  III  .in  which  are  listed  all  of  the 
parasites  of  the  brown-tail  moth  which  have  been  definitely  asso- 
ciated with  that  host  in  the  course  of  the  studies  of  imported  Euro- 
pean material,  is  constructed  in  the  same  manner  as  the  tables  of 
parasites  of  the  gipsy  mol  h  in  Japan  and  in  Europe  (see  pp.  121,  132). 
It  will  be  noted  that  the  number  and  variety  are  slightly  larger  than  of 
European  gipsy-moth  parasites,  and  that  the  species  which  are  or 
which  appear  to  be  promising  as  subjects  for  attempted  importation 
are  also  slightly  more  numerous.  Very  rarely,  however,  does  any 
one  among  them  become  as  relatively  important  as  any  one  of 
several  among  the  gipsy-moth  parasites  which  might  be  mentioned. 
Neither  has  any  lot  of  brown-tail  material  produced  so  many  para- 
sites of  all  species  (as  high  a  percentage  of  parasitism)  as  have  several 
lots  of  gipsy-moth  material. 


136 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


PARASITISM  OF  THE  GIPSY  MOTH  IN  AMERICA. 

Although  the  gipsy  moth  is  attacked  by  a  considerable  variety  of 
American  parasites  the  aggregate  effectiveness  of  all  the  species 
together  is  wholly  insignificant,  so  far  as  has  been  determined  by 
the  rearing  work  which  has  been  conducted  on  an  extensive  scale 
at  the  laboratory.  Actual  effectiveness  may  be  greater  than  indi- 
cated, however,  because  it  is  possible  that  the  caterpillars  or  pupae 
may  be  attacked  by  parasites,  the  larvae  of  which  are  unable  to  com- 

Table  III. — Sequence  of  brown-tail  moth  parasites  in  Europe. 


PARAS/TES- 


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plete  their  transformations  under  the  conditions  in  which  they  find 
themselves.  This  is  known  to  be  true  in  the  instance  of  what  would 
otherwise  be  a  very  important  parasite,  Tachina  meUa. 

In  such  instances  the  host  usually  remains  unaffected  and  the  par- 
asite perishes.  At  other  times,  as  proved  through  a  series  of  ex- 
periments carried  on  by  Mr.  P.  II.  Timberlake,  of  the  Gipsy  Moth 
Parasite  Laboratory,  in  tin4-  spring  of  the  host  may  perish 

without  exhibiting  any  external  symptoms  of  its  condition.  No 


PARASITISM   OF  (ilPSV   MOTH   IN  AMERICA. 


137 


serious  attempt  to  determine  whether  this  actually  happens  in  the 
field  has  been  made,  but  undoubtedly  it  does  occasionally  result  when 
the  parasite  larva  finds  itself  under  unnatural  surroundings.  It  is 
thus  well  within  the  bounds  of  possibility  that  effective  parasitism 
should  pass  unnoticed  in  the  course  of  investigations  in  which  reliance 
is  placed  entirely  upon  the  results  of  rearing  work. 

As  will  be  shown  in  another  place,  death  of  the  host  through  super- 
parasitism  by  a  species  fitted  to  attack  it  may  similarly  occur  without 
the  true  cause  becoming  apparent. 

A  sufficiently  large  quantity  of  the  native  caterpillars  of  the  gipsy 
moth  has  been  dissected  at  the  laboratory  to  indicate  that  such  con- 
cealed parasitism,  if  it  is  ever  a  factor  in  the  control  of  this  insect, 
is  of  rare  occurrence,  or  else  of  insignificant  proportions.  This  can 
not  be  said  of  the  pupflB  of  the  moth  in  America,  which  have  not  been 

studied  sufficiently  well  a  s  yet. 

The  following  Dative  parasites  have  been  reared  from  the  gipsy 
moth  in  Massachusetts: 

Tm  KRONIA   Fl'I.VESCENN  CRESS. 

This,  the  most  common  American  parasite  completing  its  trans- 
formations up<m  the  gipsy  moth,  was  mentioned  by  Forbush  and 
Bernald  in  I  heir  comprehensive  report  upon  u  The  ( typsy  Moth  99  under 
the  name  of  77"  inn  m  melanocephala  Brulle*.  The  true  T.  mtlano- 
C(  j>liahi  appeals  not  to  have  been  reared  from  this  host.  The  import- 
ance of  '/'.  (ill  r<  set  lis  as  a  gipsy-moth  parasite  is  indicated  by  the 
summarized  results  of  the  rearing  work  conducted  in  1910. 

Tn  his  account  of  the  parasites  of  the  forest  tent  caterpillar  {Mahi- 
cosnmd  ilisstrid  Iliibn.)  in  New  Hampshire  by  the  junior  author  it  was 
credited  a-  being  ;i  secondary  parasite  of  I'm, pin  coiMjitisitor  Say, 
and  was  not  recognized  as  a  primary  parasite.  Investigations  at  the 
laboratory  have  served  to  throw  considerable  light  upon  its  life  and 
habits,  and  it  is  now  known  to  he  a  true  primary  parasite,  but  one 
which,  [ike  Pimpla  conguisiicr  itself,  is  able  to  complete  its  transfor- 
mation, under  a  variety  of  circumstances.  The  supposed  secondary 
parasitism,  in  this  instance,  is  to  be  classified  lather  as  "superpara- 
sitism"  and  is  believed  to  result  through  the  circumstance  that  the 
primary  host  chances  to  contain  the  larva,  of  Pimpla,  rather  than 
through  the  deliberate  searching  out  by  the  parent  Theronia  of  pupse 
thus  parasitized.  In  its  relations  to  the  gipsy  moth,  which  is  not 
successfully  attacked  by  Pimpla  at  all  frequently,  Theronia  has 
always  been  a  primary  parasite  so  far  as  known. 

Pimpla  pedalis  Cress. 

One  or  two  specimens  have  been  reared  from  the  pupa?  of  the  gip>y 
moth  collected  in  the  held,  but  it  is  of  extremely  rare  occurrence  as  a 
parasite  of  this  host,  so  far  as  recent  rearing  work  indicates.    It  was 


138 


PAEASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


mentioned  as  one  of  the  more  common  parasites  by  Forbush  and 
Fernald,  but  it  is  possible  that  the  next  following  species  is  intended. 

PlMPLA  CONQUISITOR  SAY. 

Judging  from  observations  made  from  time  to  time  in  the  field 
the  pupae  of  the  gipsy  moth  are  frequently  attacked  by  this  species, 
but,  unfortunately,  the  young  larvae  of  the  Pimpla  appear  not  to 
thrive  upon  this  host  and  rarely  complete  their  transformation.  It 
is  safe  to  say  that  more  female  Pimplas  will  be  found  attacking  the 
gipsy-moth  pupae  in  the  course  of  a  day's  observations  in  the  held 
at  the  proper  season  of  the  year  than  would  be  reared  if  that  day 
were  to  be  spent  in  collecting  pupae  instead.  It  is  believed  that  the 
affected  host  usually  dies,  but  the  subject  has  not  received  the  atten- 
tion which  it  deserves.  If  it  is  true,  Pimpla  conquisitor  may  prove 
to  be  of  some  assistance  in  the  control  of  the  moth. 

Pimpla  tenuicornis  Cress. 

Recorded  as  a  parasite  by  Forbush  and  Fernald,  but  never  reared 
at  the  laboratory.  Possibly  P.  conquisitor  was  actually  the  species 
reared. 

DlGLOCHIS  OMNIVORA  WALK. 

Mentioned  by  Forbush  and  Fernald  as  of  some  consequence  as 
having  been  reared  from  this  host,  but  during  late  years  it  has  been 
so  rare  that  only  a  single  pupa  has  been  found  in  which  it  has  com- 
pleted its  transformations. 

Anisocyrta  sp. 

Mentioned  by  Forbush  and  Fernald,  but  the  record  has  not  been 
confirmed  by  later  rearing  work. 

LlMNERIUM  SP. 

A  single  cocoon,  which  was  directly  associated  with  the  remains 
of  the  host  caterpillar,  was  collected  by  Mr.  R.  L.  Webster  in  1906 
during  his  association  with  the  laboratory.  It  was  very  likely  that 
of  L.  fugitiva  Say,  but  the  fact  will  never  be  known,  because  a  speci- 
men of  Ilemiteles  utilis  Norton,  a  hyperparasite,  actually  issued. 

Apanteles  sp. 

In  1910  a  colony  of  the  caterpillars  of  the  white-marked  tussock 
moth  was  established^ upon  some  shrubbery  in  a  locality  where  the 
gipsy  moth  was  fairly  common.  The  young  caterpillars  were  spar- 
ingly attacked  by  a  species  of  Apanteles,  possibly  A.  delicatus  How., 
although  the  fact  was  not  determined.  At  the  same  time  and  place 
a  young  gipsy-moth  caterpillar  was  found  from  which  an  Apanteles 


PARASITISM   OF  GIPSY   MOTH   IN  AMERICA. 


139 


larva  bad  issued,  and  spun  a  cocoon  identical  in  appearance  with  that 
of  the  species  from  the  tussock  moth.  This  is  the  only  known 
instance  <>f  the  parasitism  of  the  gipsy  moth  by  an  American  Apan- 
tcles.and  it  is  believed  that  it  resulted  through  the  fact  that  the  par- 
asites were  first  attracted,  and  -subsequently  excited  into  oviposition, 
by  the  tussock  caterpillars, 

A  considerable  number  of  a  minute  black  and  yellow  elachertine 
secondary  parasite  was  reared  from  this  cocoon,  so  that  the  specific 
identity  of  the  Apaiiteles  originally  constructing  it  will  forever 
remain  in  doubt. 

Byntomomphy&uii  Ksnu  s  Riley. 

In  July.  l'.HHi.  Mi-.  R.  L.  Webster,  who  was  at  that  time  associated 
with  the  parasite  laboratory,  found  a  pupa  of  the  brown-tail  moth 
from  which  he  reared  a  number  of  Syntomosphyrum,  probably 
S.  esurus  Riley.  On  the  same  date,  July  IS,  the  pupa  of  a  gipsy 
moth  was  found  to  contain  the  early  stages  of  a  chalcidid  parasite, 
presumed  to  be  the  same  as  that  reared  in  connection  with  the 
brown-1  ail  moth. 

At  about  the  same  time  several  chalcidids,  apparently  of  Synto- 
mosphvrum. were  found  ovipositing  in  pupn  of  the  gipsy  moth,  but 
in  no  instance  was  the  oviposition  successful,  so  far  as  the  notes 
indicate. 

I'm  iiina  mki.i.a  Walk. 

In  their  report  on  the  gipsy  moth  Forbush  and  Fernald  speak  of 
having  collected  no  le>s  than  300  caterpillars  of  the  gipsy  moth 
bearing  Tachina  eggs  which  were  reared  through  in  the  Laboratory. 
The  most  of  these  produced  moths  ami  the  remainder  died.  \o 
parasites  were  reared. 

In  mo?  and  subsequently  large  numbers  of  caterpillars  have  been 
found  iii  the  open,  bearing  tachinid  eggs,  and  many  hundreds  have 
been  kept  under  observation  in  confinement  with  results  substan- 
tially the  same  as  those  above  mentioned.  In  one  or  two  instances, 
however,  the  tachinids  have  completed  their  transformations  and 
in  each  instance  the  species  was  Tachina  nulla.  It  is  believed,  there- 
fore, that  this  is  the  species  which  deposits  its  eggs  so  freely  and 
injudiciously. 

The  fad  thai  effective  parasitism  failed  to  result  was  attributed  by 
Forbush  and  Fernald  to  the  molting  off  of  the  eggs  before  they  had 
hatched,  and  this  doubtless  does  occasionally  happen.  Mr.  C.  IT.  T. 
Townsend  reinvestigated  the  subject  and  came  to  the  conclusion 
that  the  explanation  was  to  be  found  in  the  inability  of  the  newly 
hatched  Larvae  to  penetrate  the  tough  integument  of  the  caterpillars, 
since  he  actually  observed  such  failure  in  one  instance,  and  found 


140  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

many  caterpillars  upon  which  the  eggs  had  actually  hatched,  but 
from  winch  no  parasites  were  reared. 

That  this  explanation  may  serve  in  part  to  elucidate  the  mystery 
is  also  true,  but  still  later  observations  have  shown  conclusively 
that  the  parasite  larva?  may  gain  entrance  into  their  host  and  yet 
fail  to  mature.  Two  explanations  have  grown  where  one  was  deemed 
sufficient,  as  the  result  of  certain  technical  studies  which  have  been 
made  at  the  laboratory  during  the  past  year.  Mr.  P.  H.  Timberlake 
and,  later,  Mr.  W.  R.  Thompson  have  thoroughly  demonstrated  the 
fact  that  a  parasite  larva  gaining  lodgment  in  an  unsuitable  host 
may  die,  and  its  body  may  be  in  great  part  absorbed  through  action 
of  the  phagocytes  without  causing  the  host  obvious  inconvenience. 
This  very  likely  takes  place  with  Tachina  mella  in  its  relations  with 
the  gipsy  moth  and  is  probably  a  better  explanation  of  its  failure  to 
become  an  elective  parasite  than  any  other  which  has  yet  been  put 
forward. 

Mr.  Thompson  also  discovered  another  most  remarkable  and 
peculiar  phenomenon  in  connection  with  parasitism  by  those  tachi- 
nids  the  larvae  of  which  inhabit  integumental  funnels  similar  in 
character  to  those  formed  by  Tachina.  These  funnels  appear  to  be 
formed  as  a  direct  result  of  the  tendency  of  the  skin  to  grow  over 
and  heal  the  wound  caused  by  the  entrance  of  the  tachinid  maggot 
into  the  body  of  the  host.  This  wound  is  kept  open  by  the  larva 
itself,  and  as  a  result  the  growing  integument  takes  the  form  of  an 
inverted  funnel,  more  or  less  completely  surrounding  the  parasitic 
maggot,  which  continues  to  breathe  through  the  minute  orifice  in  its 
apex.  When  the  caterpillar  molts  the  old  skin  is  usually  torn  away 
from  around  this  opening,  leaving  the  maggot  in  situ  and  unaffected, 
but  occasionally  its  attachment  to  the  funnel  may  remain  so  strong 
as  to  result  disastrously  for  the  maggot,  and  the  whole  funnel,  maggot 
included,  may  be  withdrawn.  Thus,  not  merely  the  eggs  may  be 
molted  off,  but  the  internal  feeding  maggots  which  have  hatched 
from  the  eggs  may  be  molted  out  and  perish. 

ACH^TONEURA  FRENCHII  WlLL. 

A  very  few  specimens  of  this  species  have  been  reared  from  time 
to  lime  in  the  course  of  the  work  at  the  laboratory.  It  is  probable 
that  the  species  is  synonymous  with  that  mentioned  by  Forbush 
and  Fernald  under  the  name  of  Achsetoneura  fernaldi. 

EXORISTA  B  LAN  DA  0.  S. 

Occasionally  reared  as  a  parasite  of  the  gipsy  moth. 


PARASITISM    OF  (ilPSV   MOTH   IN  AMERICA. 


141 


Undetermined  Tachinids. 

Dr.  S.  W.  Williston.  in  reporting  upon  a  collection  of  Diptera  reared 
fioin  the  gipsy  moth  in  Massachusetts  and  sent  to  him  in  1S<)1  by 
Dr.  Fernald.  stated  that  there  were  present  two  species  of  Exorista 
and  four  of  Phorocera.  Unfortunately  these  specimens  appear  to 
have  been  lost  before  being  definitely  determined.  No  such  variety 
of  tachinids  lias  been  reared  from  this  host  in  Massachusetts  during 
recent  years,  but  several  species  as  yet  undetermined,  or  represented 
only  by  unfamiliar  puparia,  are  in  our  collection. 

SUMMARY  OF    REARING   WORK  CARRIED   ON    AT   THE    LABORATORY  IN 

1910. 

Iii  Tables  IV  and  V  are  t ho  condensed  results  of  a  pari  of  an 
extensive  series  of  rearing  experiments  primarily  instituted  for  the 
purpose  of  determining  the  present  status  of  the  introduced  parasites 
of  the  gipsy  moth  in  America  in  1910.  They  also  serve  excellently 
as  an  indication  of  the  effectiveness  of  parasitism  by  native  species. 
In  this  respect  they  are  typical  of  the  results  secured  from  similar 
work  in  previous  years! 


Table  IV.— Results  of  rearing  work  in  1910  to  detennim  progress  of  ini ported  parasites 
and  pre  rah  nee  of  parasitism  hg  natin  parasites  of  gi  jtsg-ntoth  pa  pit 


LillMH 

raton 
No. 

Localities. 

Niim- 
bec  of 

<liv|»ar. 
pupa-. 

Mot  h  i  reared 

Parasites  reared. 

Scano- 
phagid 
puparia. 

Male. 

l-'rliiale. 

Blepha- 
r.pa  MO- 
tellata. 

2 
1 

2 

The- 
ronia 
tahrflB- 
ceius. 

Camp* 

silura 

Bonoto- 
nata. 

MlM-l- 

laneous 
tachi- 
nids. 

2185 
2188 
2187 

21S* 

•21 VI 
2190 
2190a 

North  A  lit  lover. . . 
Melrose  

1,700 
500 
1.S00 

I,  MX) 

1.000 
SOD 

i  106 
800 
300 

2>2 
100 
1,060 
1.700 
1.047 
1.(100 
1.000 

1,250 
580 

1.700 
500 
400 

1.700 
000 
300 

1.000 

1.100 
900 
500 
500 

1,100 

1.222 

IV, 
tifCi 
|S2 
412 
1215 
4 

159 
108 
09 
87 
274 
312 
379 
81 
147 
2.-.:; 
212 
442 
201 
152 

354 
82 
85 
143 
118 
198 
229 
8L 
193 

259 
l.Vt 
21  *  l 
401 
250 
217 
3S 
t,s 
92 
115 
22 
172 
211 
127 
144 
7s 
209 
102 
218 
125 
133 
340 
87 
49 
401 
323 
215 
102 
104 
156 

North  Andover. . . 
stoneham  

3 
5 
2 

1 

2 

2 

Sauna  

3 
1 

Y\  akefield  

 do  

1 

1  12 

2191 

2192A 

219211 

2192C 

2193 

2194 

2190 

2197 

219*) 

22X0 

2281 

2282 

2283 

22.s  1 

22V> 

22NO 

22S7 

2289 

2290 

2291 

2293 

2294 

2295 

North  Andover. . 

Wohnrn  

1 

North  Andover..  . 
Saugus  

2 

1 

Melrose  -  

1 

Stoneham  

Beverly  

 I 

13 
5 
10 

 do  

2 
2 
1 

17 
1 

Saugus  

1 

3  1 

North  Andover... 

 do  

Beverly  

8 

*  1 

0 



 do  

Gloucester  

3 

52 

5 
1 

Beverly  

 do  

North  Andover. .. 

 do  

 do  

3 
4 

1 

2 

Beverly  

 do  

:  

2 

2 

Middleton  

Total  

27.215 

7.531 

|   5.342  16 

47 

18 

4 

53 

1  1 're  pupa?. 

2  l'artly  from  another  locality. 

3  Tachiua-like  species,  puparium. 


*  Exorista  blanda. 

5Onetachina-likeandone  unknownnativespecies, 
puparia. 


142 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Table  IV  includes  the  results  of  rearing  work  in  which  caterpil- 
lars collected  in  the  open  were  used.  A  large  proportion  of  the 
collections,  probably  half  or  more,  was  from  localities  in  which 
Compsilura  concinnata  is  not  as  yet  established,  although  it  will 
probably  have  extended  its  range  to  include  these  by  the  end  of 
another  year.  It  will  be  observed,  however,  that  the  number  of  the 
Compsilura  reared  is  very  far  in  excess  of  that  of  any  native  tachinid 
or  other  parasites  attacking  this  caterpillar  as  a  host.  This  is  espe- 
cially encouraging  in  view  of  the  fact  that  one  year  ago  less  than 
one  one-hundredth  of  the  proportionate  number  of  Compsilura  were 
reared  under  similar  circumstances,  and  only  from  material  collected 
over  a  much  more  restricted  area. 


Table  V.— Results  of  rearing  icork  in  1910  to  determine  -progress  of  im ported  parasites 
and  prevalence  of  parasitism  by  native  parasites  of  gipsy-moth  caterpillars. 


Laboratory  No. 

Localities. 

Number  of  caterpillars. 

Number   of  p  up  ae 
reared. 

Number 
of  moths 
reared. 

Number  of  parasites  reared. 

03 

"31 

Female. 

2  * 

-  03 

S 
P 

O  o 

O  o 

PI  - 

%M 

03  ._ 

03       1  * 
o  §  = 

03  . 

—  \r. 

-  | 
O  p 

—  a 

Blepharipa 
scutellata. 

4317 
4330 
4332 
4333 
4334 
43.37 
4340 

Welleslev  

1.029 
535 

2.110 

3.000 

2.000 
800 

1.250 
600 

2. 000 
300 
100 

1,500 
125 
110 

1.000 

1.125 
500 
230 
400 

1.000 
250 
800 

150 
150 
425 
300 
100 
53 
341 

158 
298 
716 
962 
599 
300 
846 
308 
902 
234 

54 
566 

69 

14 
818 
934 
207 

56 
"20 
338 

61 
286 

103 
65 

181 

191 
37 
6 

281 

15 
43 
419 
371 
59 
20 
234 
124 
363 
18 
5 
30 

1 

245 
150 
11 
4 
1 
29 
4 
21 

11 

9 
29 
18 

2 

13 
81 

115 
177 

88 
245 
144 
317 
202 

34 
199 

25 
6 

344 
301 
125 
30 
5 

139 
22 
106 

43 

11 
lit 
128 

22 
4 

42 

Stoneham  

9 

Welleslev  

8 
4 

 do  

Stoneham  

108 
73 

 do  

Welleslev  

3 

4341 
.  4349 

Swampscott  

1 

6 

2  1 

4351 A 

4351b 

4352 

4353 

4354 

4356 

4359 

4360 

4362 

4366 

4367 

4369 

4370 

4372 

4373 
4377 
4378 
4386 
4387 
4392 

Medford  

6 

Winchester  

Dan  vers  

6 

2 
12 

Winchester  

1 

Wellesley  

2 
1 
1 

2  3 

38 
34 

 do  

Stoneham  (?)...  . 
Beverly  

59 

1 

1 

Lexington  

2 
15 

5 
14 

21 

Salem  

Marblehead  

Salem  

. 

31 

Stoneham - 
Woburn  

Welleslev  

3  1 

Xahant  

1 
1 
1 
1 

Winthrop  

Burlington  

Lexington  

Manchester  

21 

Total 

22.  283 

9.610 

337 

25 

2 

*!  14 

1 

1  The  identity  of  this  tachinid,  the  puparia  of  which  resemble  those  of  tachina,  but  which  hibernates  as  a 
pupa,  is  wholly  unknown.    The  adult  has  never  been  reared. 

2  From  near  site  of  colony  of  1910.    Recovery  of  no  significance.    Masses  of  cocoons  counted. 

3  A  few  pupae  included  in  this  collection. 


In  Table  Y  arc  included  results  of  rearing  work  in  which  collections 
of  gipsy-moth  pupffi  were  used.  These  were  largely  made  in  local- 
ities near  the  center  of  colonization  of  BlepTwbripa  SCUteUata  of  the 
same  year.    The  number  of  Blepharipa  secured  is  higher  in  propor- 


PARASITISM  OF  BROWN-TAIL  MOTH  IN  AMERICA. 


143 


tion  to  the  number  of  pupa?  collected  than  would  be  the  case  had 
these  collections  been  made  irrespective  of  the  localities  where  the 
species  was  so  recently  colonized. 

Parasitism  by  Theronia  is  somewhat  less  on  the  average  than  in 
some  other  years  when  similar  studies  have  been  made.  At  times 
it  has  amounted  to  as  much  as  '2  per  cent. 

Sarcophagids  are  not  considered  as  parasites,  but  rather  as  scav- 
engers.   Their  true  status  is  yet  to  be  determined,  however. 

Com psilura  concinnata  is  not  commonly  secured  from  the  pupa3, 
and  in  one  instance  in  which  more  than  an  insignificant  number  of 
this  species  was  recovered  the  collection  consisted  of  caterpillars, 
which  had  prepared  for,  but  not  undergone,  pupation. 

Xo  Monodontomems  were  reared  from  any  of  the  collections  of 
pupae  included  in  Table  IV,  nor  has  the  species  ever  been  recovered 
from  counted  lots  of  pupa?  collected  in  the  open.  It  was  found  in 
as  in  MMK),  by  the  examination  of  unhatched  pupffi  after  the 
most  of  those  remaining  healthy  bad  produced  the  moths,  and  issued 
in  unsatisfactory  numbers  from  collections  of  pupa4  made  at  the  same 
time.  These  were  not  counted  at  the  time  of  collection,  and  on  that 
account  were  not  included  in  the  table. 

PARASITISM  OF  THE  BROWN-TAIL  MOTH  IN  AMERICA. 

The  brown-tail  moth  in  America  is  subjected  to  a  considerably 
higher  percentage  of  native  parasitism  than  is  the  gipsy  moth,  but  at 
the  same  time,  as  will  appear  in  the  summarized  results  of  the  rearing 
work  in  11)10,  the  aggregate  i>  scarcely  sufficient  to  be  considered  as 

consequential. 

The  following  species  have  been  reared,  and  doubtless  the  list  will 
receive  additions  in  the  near  future. 

TBICHOGRAMMJ  HUtTXQSA  RlLEY. 

A  very  considerable  percentage  of  the  egg  masses  collected  in  the 
open  is  parasitized  by  this  species,  hut  because  of  the  inability  of 
the  parasite  to  attack  any  but  the  more  exposed  eggs  in  a  ma^s,  the 
actual  percentage  of  parasitism  is  insignificant. 

LlMNERIUM  CLISIOCAMP.E  WEED. 

In  1907  a  single  specimen  of  this  common  parasite  of  the  tent 
caterpillar  was  reared  from  a  brown-tail  caterpillar  collected  in 
Exeter,  N.  H.  One  or  two  other  rather  doubtful  records  have  been 
made  since.  It  is  unquestionably  not  an  important  parasite  of  the 
brown-tail  moth 


144 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Anomalon  exile  Prov. 

Quite  commonly  reared  as  a  parasite  of  the  tent  caterpillar  and  not 
infrequently  as  a  parasite  of  the  brown-tail  moth,  apparently  attack- 
ing the  caterpillars  before  pupation  and  probably  while  they  are  still 
very  }^oung.  Its  frequency  as  a  parasite  of  the  brown-tail  is  well 
indicated  in  Table  VI  (p.  147),  which  records  the  results  of  the 
summer's  rearing  work  of  1910. 

Theronia  fulvescens  Cress. 

This  is  probably,  as  in  the  case  of  the  gipsy  moth,  the  most  common 
native  hymenopterous  parasite.  No  attempt  has  been  made  to  deter- 
mine whether  it  is  commonly  primary  or  secondary  in  this  connection, 
but  it  is  presumably  primary  in  the  majority  of  instances. 

PlMPLA  CONQUISITOR  SAY. 

The  pupas  of  the  brown-tail  moth  seem  to  afford  much  more  suitable 
conditions  for  the  development  of  the  Pimpla  larva?  than  do  the  pupae 
of  the  gipsy  moth.  In  consequence  this  Pimpla  is  frequently  reared 
and  is  probably  about  as  important  as  a  parasite  of  the  brown-tail 
moth  in  America  as  are  the  European  species,  Pimpla  examinator 
and  Pimpla  instigator ,  abroad. 

Pimpla  pedalis  Cress. 

This  species  is  never  so  common  as  Pimpla  conquisitor  in  its  asso- 
ciation with  the  brown-tail  moth.  It  is  apparently-identical  in  habit 
with  the  more  common  species,  but  if  results  in  studies  in  parasitism 
of  other  hosts  are  to  be. excepted,  it  is  more  apt  to  occur  in  forests  and 
woodland  than  in  open  country. 

DlGLOCHIS  OMNIVORA  WALK. 

At  times  Diglochis  is  a  common  parasite  of  the  brown-tail  moth 
pupse,  but  in  1910  it  was  unexpectedly  scarce  in  Massachusetts, 
although  it  seemed  to  have  been  much  more  common  in  Maine,  judg- 
ing from  the  small  amount  of  material  which  has  been  received  from 
that  Slate. 

Syntomosphyrum  esurus  Riley. 

Of  irregular  occurrence  as  a  parasite  of  the  brown-tail  moth,  but 
among  the  more  effective  of  the  native  species  in  1910.  It  was  lirst 
reared  in  1906  by  Mr.  li.  L.  Webster,  while  associated  with  the  lab- 
oratory, and  not  again  encountered  until  1910,  when  large  numbers 
issued  from  material  collected  in  certain  localities,  as  will  be  seen  in 
Table  VI  which  shortly  follows. 


PAlUiSITiSM  OF  BKOWS-TAIL  MOTH  IX  AMERICA. 


145 


Chalcis  sp. 

Upon  several  occasions  specimens  of  Chalcis  have  issued  from 
cocoons  of  the  brown-tail  moth  collected  in  the  open.  The  species 
has  not  been  definitely  determined  nor  compared  with  Chalcis  ovata, 
because  it  is  thought  likely  at  the  present  time  that  two  species  may 
be  confused  under  that  name.  One  of  them  is  believed  to  be  a  pri- 
mary parasite  of  lepidopterous  pupae  and  the  other  to  be  essentially 
a  secondary  parasite  attacking  tachinid  puparia. 

EUPHOROCERA  CLARIFENNIS  MACQ. 

Several  times  reared  from  brown-tail  caterpillars  collected  in  the 
fieldj  but  always,  apparently,  rare  in  this  connection. 

Tachina  mella  Walk. 

Never  a  common  parasite  in  connection  with  this  host.  Usually 
about  on  a  par  with  Buphorocera  and  without  economic  significance. 

Phorocera  saundersii  WlLL. 

A  single  specimen  thus  determined  by  Mr.  Thompson  w  as  reared 
in  1910  under  circumstances  which  quite  conclusively  indicate  this 
host  relationship. 

EXORISTA  noARMI.K  GOQ. 

Like  the  above,  only  a  single  individual  of  this  species  has  been 
reared  from  brown-t  ail  caterpillar  collections,  but  under  circuinst  ances 
which  were  not  so  decisive  as  in  the  last-mentioned  instance.  Mr. 
Thompson  is  authority  for  this  determination  also. 

Undetermined  Tachinid:  "Native  Parasite  of  cm  kysourwka." 

One  of  the  most  remarkable  instances  of  attack  oil  an  unsuitable 
host  by  a  tachinid  parasite  is  that  of  the  species  which  in  the  labora- 
tory not  \s  is  always  referred  to  as  above,  upon  the  caterpillars  of  the 
brown-tail  moth.  The  history  of  this  species,  the  identity  of  which 
is  very  much  in  doubt,  is  in  certain  respects  comparable  to  that  of 
TacJiuia  mella  in  its  relations  to  the  gipsy  moth.  As  may  be  seen  by 
tln^  summarized  results  of  the  rearing  work  in  1910  (Table  VI),  it 
is  not  infrequently  a  parasite  of  some  little  consequence,  and  in  all 
many  hundreds  of  its  larva3  have  been  secured  from  field  collections 
of  brown-tail  caterpillars. 

Invariably,  however,  these  larvae  died  without  forming  perfect 
puparia.  For  a  Ion";  time  it  was  thought  that  this  was  due  to  unfa- 
vorable surroundings  at  the  time  when  pupation  was  attempted  and 

!XHJ77°—  Bull.  IH — 11  10 


146 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


that  if  the  larvae  were  allowed  to  enter  damp  earth  as  soon  as  they 
issued  from  the  host,  better  results  might  be  obtained.  In  order  to 
provide  for  this,  the  style  of  rearing  cage  which  is  shortly  to  be 
described  and  figured,  was  devised.  With  its  aid  we  were  enabled 
to  secure  a  large  proportion  of  the  parasite  maggots  within  a  few 
moments  after  they  had  finally  separated  themselves  from  the  cocoon 
which  the  host  invariably  spins  before  dying,  and  these  were  given 
every  advantage  which  could  be  afforded  to  assist  in  the  successful 
completion  of  their  transformations.  The  results,  however,  were 
always  the  same  and  not  one  perfect  puparium  has  been  secured. 

The  reasons  for  this  may  not  be  far  to  seek,  but  the  chances  are 
that  it  will  be  a  long  time  before  an  adequate  explanation  is  afforded. 
When  it  was  found  that  the  larvse  failed  to  pupate  under  the  most 
favorable  conditions,  they  were  carefully  examined  on  the  supposi- 
tion that  death  might  possibly  accrue  through  the  action  of  the  pois- 
onous spines  into  which  they  must  necessarily  come  in  direct  contact 
in  leaving  the  host  cocoon.  It  was  at  once  discovered  that  there  was 
invariably  a  number  of  minute  reddish  spots  scattered  irregularly, 
and  more  or  less  abundantly,  over  the  whole  or  a  part  of  the  body. 
It  looked,  at  first,  as  though  these  spots  might  be  the  result  of  contact 
with  the  poisonous  spines,  but  upon  further  examination  it  was  found 
that  they  were  of  a  character  which  could  hardly  be  attributed  to 
this  cause.  They  are  somewhat  variable  in  size  and  seem  to  consist 
of  a  thickening  of  the  epidermis  which  becomes  slightly  raised,  shining, 
and  brick-red  in  color.  No  attempt  has  been  made  as  yet  to  deter- 
mine whether  they  are  present  in  the  maggot  before  it  leaves  the 
body  of  its  host,  but  little  doubt  is  felt  that  they  will  be  found  when 
such  examination  is  made. 

That  these  spots  are  directly  or  indirectly  responsible  for  the  failure 
of  the  maggot  to  pupate  is  well  indicated  by  the  study  of  the  numerous 
half-formed  puparia  which  result  from  the  attempt  on  the  part  of  the 
larva  of  the  parasite  to  do  so.  These  are  all  more  or  less  larviform, 
but  occasionally  one  is  found  one  end  of  which  is  smooth  and  rounded 
exactly  as  though  pupation  had  successfully  resulted,  while  the  other 
is  shrunken  and  withered,  resembling  a  dead  larva.  Careful  exami- 
nation revealed  that  in  such  specimens  the  reddish  spots  were  absent 
from  the  perfect  portion  and  present  in  the  withered. 

SUMMARY  OF  REARING  WORK  IX  1910. 

The  accompanying  tabulated  results  (Table  VI)  of  an  extensive 
series  of  rearing  experiments  for  the  purpose  of  determining  the 
progress  of  the  imported  parasites  of  the  brown-tail  moth  also  indi- 
cate the  extent  to  which  that  host  is  attacked  by  native  parasites. 


PARASITISM  OF  BROWN-TAIL  MOTH   IN   AMERIC  A. 


U7 


E 


'r-  = 

T  -  L-  i 

X    -A  ~ 


-   -  r 

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C  —  - 

5  =  =  P 


3  Ej 
z  >  c 


CN-fl  


~  CM  r  i  -! 


r~  —  '~'"'-i--rt--c-:  —  s.  \~  —  ~  -  ~  s  r     —  cm     —  — 
—  —  ^  r'  —  i-Mi-MC  cm      r  i  -  i  -  -  — 


O  /"  ~  i  i  -  -  —  —  r  r  —  -  r  ;  m  /  - 


-c  >c     '>-.  ■:  ti  -  ~~  >T  .7         ::  ^  ^  ^  ^  -r  —  ^  —  ^  ^  y.  cm  :c  cj  cm  >'.  >~      c  cm 


M  i-, 


—     .  v- 

t  d  § 


=  1  =  =  >■£  =  C  £  t  =  P  i  =  ~T  =       i  §.E£  =  =  £  £~  c  =  £ 

x  S  -t  x  -  x  <  fr-  2i  s  -  ^  J  x  £  <  ^  -  3  55  x  S  ^  w  J  x.  J  i.--.-.  C  -  > 


cm  cm  cm  cm  cm  cm  cm  cm  cm  cm  cm  cm  cm  cm  cm  cm  cm  o  ri  cm  cm  cm  cm  cm  cm  cm  cm  cm  cm  cm  cm  cm  cm  cm 


148 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Tachi- 

Exor- 

ista 
boar- 

Phoro- 
cera 
saun- 
dersii. 

u 

I 

omniv- 
ora. 

:  is 

:  ;  '  :  : 

! 

Synto- 

phy- 
rum 

.   !   .  • 

:        I  i 

:9  :S3  :  :  : 


Native 

jii 



N  rH 

•3  :  :  : 

Thero- 

nia 
fulves- 

!       t  y—\       !  ^         (N  "O       j  ! 

HH      '  <N  i-H  <M 

H 



Pimpla 
con- 
quisi- 
tor. 

p-i  I  eo  '•  >  '• 

03  :23  : 

!  ;  io  .' 

CM     •     '  CM     •  ' 

:        ;  :  1 

! 
I 

Mono- 
don- 

tome- 
rus 

sereus. 

■     •  CO     •  • 

.    .    .  r~  . 

3  : 

-.3    •    •  CO 

!   !<n   '.   '.  ! 

m 

• 



>o  — 1  CO    '•    '•  i 

 ; 

.    .  m   .   .   .  . 

m 

.  . 

I 

Comp- 
silura 
con- 
cin- 
nata. 

■  ■ 



Moths 
reared. 

4 

i 

iWflll!ll1iJl1lSiiIlil!f 





iiiiliiiiliillllilliiiiiiiiiii 


PARASITISM  OF  BROWN-TAIL  MOTH  IX  AMERICA.  149 


s 

S3 
^« 

CM 

!  -r 

8 

•  es 

—  —  — 

— 

p 

co 

 J 

i 

a 

t- 

es 

~  z  —  x  5. 

3.851 

24,350  3,955 

i 

i-* 

3  B 
~  ~Z 

S  : 
1  o  . 

1:1 

Total  

150 


PARASITES  OF  GIPSY  AKD  BKOWN-TAIL  MOTHS. 


As  may  be  noted  by  reference  to  the  table,  the  imported  parasites 
are  beginning  to  become  sufficiently  abundant  so  that  parasitism  by 
them  will  compare  favorably  with  that  by  American  species,  but  are 
not  as  yet  so  abundant  as  to  exceed  the  American  species  in  relative 
effectiveness.  The  table  as  presented  does  not  indicate  at  all  accu- 
rately the  actual  status  of  the  several  species  of  parasites  mentioned, 
on  account  of  the  difference  in  the  condition  of  the  material  at  the 
time  of  collection. 

Compsilura,  for  example,  is  much  more  apt  to  leave  the  cater- 
pillars before  they  spin  for  pupation,  and  the  same  is  true  of  Meteorus. 
Monodontomerus,  Pimpla,  Theronia,  etc.,  never  attack  caterpillars 
before  spinning,  and  Monodontomerus  and  Theronia  frequently 
reserve  attack  until  some  little  time  after  the  host  has  pupated.  As 
it  stands,  parasitism  by  Monodontomerus  is  about  equal  to  that  of 
Theronia  and  in  excess  of  that  by  Pimpla  or  Anomalon.  Parasitism 
by  Compsilura  is  distinctly  more  effective  than  that  by  all  of  the 
other  native  tachinid  parasites  of  the  caterpillars.  Meteorus  is  much 
more  common  than  indicated  in  the  limited  territory  over  which  it  is 
now  known  to  exist,  and  the  specimens  reared  represented  the  second 
generation  of  adults  to  develop  upon  the  brown-tail  moth  in  1910. 

Apanteles  lacteicolor  Yier.  is  not  represented  in  these  collections, 
since  it  does  not  attack  caterpillars  so  large  as  those  involved. 

In  carrying  on  this  work  several  styles  of  rearing  cages  were  used, 
of  which  one  was  devised  for  the  special  purpose  of  securing  the 
tachinid  parasites  with  the  minimum  of  exposure  to  the  effects  of 
the  irritating  hairs  of  the  brown-tail  caterpillar.  This  worked  very 
satisfactorily,  and  since  it  may  possibly  be  found  of  service  in  con- 
ducting similar  work  elsewhere,  the  following  description  is  presented: 

The  basis  of  this  cage  (see  fig.  10)  consisted  of  a  box  of  stiff  paste- 
board 8  inches  square  and  12  inches  high.  About  4  inches  from  the 
top  a  stiff  paper  funnel  (a)  was  fitted  and  held  in  position  by  the 
cleats  (6),  which,  in  turn,  were  fastened  to  the  sides  of  the  box  by 
broadheaded  upholsterer's  tacks  driven  in  from  the  outside.  These 
cleats  served  to  support  the  tray  (c),  which  just  fitted  into  the  cage. 
The  bottom  of  this  tray  was  covered,  in  some  instances  with  coarse 
mosquito  netting,  and  in  others  with  a  wire  screen  of  J-inch  mesh. 
Two  holes  in  the  side  of  the  tray  corresponded  with  two  1-inch  holes 
in  the  side  of  the  box,  and  these  in  turn  with  similar  holes  in  a  wooden 
strip  0/),  which  was  fastened  on  the  outside.  When  the  tray  was  in 
position,  paper  cones  (li)  and  large  glass  tubes  (g)  were  inserted  in 
these  holes. 

The  stiff  paper  funnel  (a)  had  its  apex  inserted  into  another  hole 
bored  diagonally  in  a  similar  wooden  strip  which  was  fitted  in  the 
bottom  of  the  cage.  Inside  of  this  hole  a  stiff  paper  cone  (formed 
like  It  by  rolling  up  a  section  of  a  strip  of  paper  cut  to  a  circular 


Parasitism  of  brown-tail  moth  in  America. 


151 


shape)  was  held  in  position  by  a  tack  which  passed  through  it  into 
the  wooden  strip.  The  end  of  this  cone,  passing  through  the  bottom 
of  the  cage,  permitted  a  third  glass  tube  (/)  similar  to  the  two  above 
mentioned,  to  be  held  in  position.  Xo  further  support  to  this  tube 
was  Deeded  than  that  afforded  by  the  cone  itself. 

In  using  this  cage  a  mass  of  cocoons  of  the  brown-tail  moth  was 
placed  in  the  tray,  and  the  cover  was  put  on  with  the  several  tubes 
in  position.  Tachinid  maggots  issuing  from  the  prepupal  caterpillars, 
08-  pupflB  contained  in  the  cocoon  mass,  in  attempting  to  seek  the 
earth  would  pass  through  the  bottom  of  tin4  tray  and  be  conducted  by 
the  still"  paper  funnel  into  the  lower  tube,  where  they  were  quickly 
noticed  and  easily  re- 
moved. All  other 
parasites,  as  well  as 
the  brown-tail  moths 
themselves, when  they 
emerged,  were  at- 
tracted by  the  light 
into  the  two  upper 
tubes,  and  could  be 
similarly  removed 

with  little  difficulty. 
(See  PI.  Y.  fig.  I.) 

By  the  aid  of  this 

contrivance  we  were 

enabled    to  secure  a 

quantity  of  the  larvae 
of  the  unknown  tach- 
inid. already  men- 
tioned, within  a  few 
minutes  after  they 
had  issued  from  the    Fio.  10.-^-Baaring  eage  for  tachinid  parasites  of  the  brown-tail  moth* 

i       i  i   ,i      m  i        I  a.  Paper  funnel;  b,  cleats  holding  paper  funnel  in  position;  r,  tray: 

IlOSl,  ana  ineiel>\  ae-  nooden  strip  un  outside  of  cage;  e,  paper  cone  connecting  paper 

temuned  that  the  fail-       funnel  a  and  glass  tube  /;  /(,  //.  paper  funnels  supporting  glass 

ureof  this  species  to     tob*''*  <)riKinal 

pupate  was  in  no  way  due  to  the  unnatural  surroundings.  Some- 
times the  tubes  were  partly  filled  with  damp  earth,  in  order  that 
these  larva4  might  immediately  come  in  contact  with  it,  and  at  other 
times  the  larvae  were  removed  as  soon  as  they  dropped  and  placed 
upon  earth  similar  to  that  which  they  would  naturally  have  encoun- 
tered had  they  issued  from  cocoons  in  the  field  under  wholly  natural 
conditions. 

The  use  of  these  cages  also  saved  a  large  amount  of  exceedingly 
painful  work  which  would  otherwise  have  been  necessary  in  determin- 
ing whether  or  not  Parexorista  chelonidb  was  present  in  any  of  the 
field  collections. 


152 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS, 


IMPORTATION  AND  HANDLING  OF  PARASITE  MATERIAL. 

Since  insects  like  the  gipsy  moth  and  the  brown-tail  moth  are  sub- 
jected to  the  attack  of  different  species  of  parasites  at  different  stages 
in  their  development,  it  has  been  necessary,  in-order  to  secure  all  of 
these,  to  import  the  host  insects  in  as  many  different  stages  as  pos- 
sible and  practicable.  If  the  present  experiment  in  parasite  intro- 
duction is  brought  to  a  successful  conclusion,  it  will  undoubtedly 
encourage  the  undertaking  of  other  experiments  in  which  similarly 
imported  pests  are  involved.  Even  should  it  fail,  from  a  severely 
practical  standpoint,  and  the  complete  automatic  control  of  neither 
the  gipsy  moth  nor  the  brown-tail  moth  should  be  effected,  it  seems 
to  us  that  the  technical  results  already  achieved  are  sufficient  to  give 
encouragement  rather  than  the  opposite  to  similar  undertakings  in 
the  future.  It  is  therefore  desirable  to  describe  in  some  detail  the 
various  methods  employed  for  the  importation  and  subsequent 
handling  of  the  parasite  material. 

With  very  few  exceptions  the  methods  first  employed  proved  more 
or  less  unsuitable.  Sometimes  they  were  entirely  discarded;  usually 
they  were  modified  to  suit  the  exigencies  of  the  occasion.  Some- 
times these  modifications  were  in  comparatively  unimportant  par- 
ticulars which  would  scarcely  be  pertinent  to  any  other  insect  than 
the  gipsy  moth  or  the  brown-tail  moth,  and  realizing  this  there  will 
be  no  attempt  in  such  cases  to  enter  into  lengthy  descriptions.  At 
other  times  radical  modifications  have  been  found  necessary  on 
account  of  unforeseen  difficulties  which  would  be  likely  to  occur  in 
pretty  nearly  any  other  undertaking  along  anytliing  like  similar  lines. 

EGG  MASSES  OF  THE  GIPSY  MOTH. 

The  importation  of  egg  masses  of  the  gipsy  moth  (see  PI.  VI) 
from  European  sources  has  been  attended  with  no  difficulty  whatever, 
beyond  that  of  securing  the  collection  of  these  eggs  in  sufficiently 
large  quantities.  Any  style  of  package,  provided  that  it  were  suffi- 
ciently tight  to  prevent  loose  eggs  from  sifting  out,  was  as  good  as 
another,  and  any  one  of  the  established  means  of  transportation 
served  the  purpose. 

In  the  case  of  shipments  from  Japan  serious  difficulties  were 
encountered.  One  of  the  parasites  peculiar  to  that  country  and 
unknown  in  Europe  invariably  issued  en  route  and  died  without 
reproducing.  Various  attempts  to  overcome  this  difficulty  without 
having  recourse  to  cold  storage  failed  and  it  was  only  after  cold- 
storage  facilities  were  perfected  and  used  that  living  parasites  of  this 
species  were  secured  in  numbers. 

As  in  the  instance  of  similar  shipments  from  Europe,  no  special 
form  of  package  was  required,  but  at  the  same  time  a  word  of  appre- 


But.  91,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agriculture. 


Plate  V. 


Fiq.  2.— Box  Used  in  Shipping  Immature  Caterpillars  of 
the  Gipsy  Moth  from  Japan.  (Original.) 


IMPORTATION   AND  HANDLING  OF  PARASITE  MATERIAL.  153 


ciation  must  be  said  for  the  wonderful  eare  with  which  the  Japanese 
entomologists  packed  the  egg  masses  for  shipment.  Good-sized  and 
wonderfully  well-constructed  wooden  boxes  were  used  and  each  mass 
was  wrapped  separately  in  a  small  square  of  soft  rice  paper. 

Considering  the  ease  with  which  egg  masses  of  the  gipsy  moth 
ought,  theoretically,  to  be  obtained  and  shipped  to  the  laboratory, 
the  number  received  in  response  to  the  requests  which  were  made  for 
their  collection  and  shipment  was  astonishingly  small  during  the 
first  two  winters.  Up  to  that  time  only  a  very  few  dead  parasites 
of  an  undescribed  genus  and  species  had  been  received  from 
Japan,  and  none  at  all  had  issued  from  any  of  the  few  European 
importat  ions. 

In  190S  the  several  lots  of  eggs  were  placed  in  small  tula4  cages  of 
the  ordinary  type  and  the  caterpillars  killed  as  they  issued.  Some 
time  after  the  eggs  had  hatched  a  few  parasites  began  to  appear 
simultaneously  from  the  European  and  Japanese  material,  which 
proved  upon  examination  to  he  Annstdtu*  hifasciatus  in  each  instance. 
Later  a  few  Tyndarichus  navse  were  reared  from  the  Japanese  eggs 
and  supposed,  rightly  enough,  to  he  secondary,  although  probably 
not,  as  at  first  supposed,  upon  Anastatus.  This  hyperparasitism 
was  by  no  means  certain,  and  it  was  resolved  to  determine  the*  fact 
definitely  the  following  fall  and  winter,  provided  additional  importa- 
tions could  be  secured.  The  desired  material  was  imported  and  an 
exhaustive  study  of  the  parasites  which  were  present  was  made,  with 
the  result  that  the  five  species  were  reared  and  their  host  relations  as 
well  as  their  relations  one  to  another  definitely  determined.  The 
execution  of  this  project  proved  to  he  much  more  tedious  than  was 
expected,  and  was,  in  fact,  (he  feature  of  that  winter's  work.  Fur- 
ther mention  of  the  investigation  will  appear  in  the  discussion  of 
Schedius  kuvanx. 

GIPSY-MOTH  CATERPILLARS,  FIRST  STAGE. 

In  the  spring  of  1907  an  attempt  was  made  to  import  the  cater- 
pillars of  the  gipsy  moth  in  their  first  instar.  and  a  considerable  num- 
ber was  received  from  several  different  localities.  The  experiment 
was  not  a  success  and  was  not  repeated.  The  mortality  was  heavy 
en  route  and  only  a  small  proportion  of  the  caterpillars  would  feed 
aft ei-  receipt.  Some  few  were  carried  through  to  maturity,  hut  QO 
parasites  were  reared. 

It  is  very  probable  that  if  recourse  were  had  to  cold  storage, 
caterpillars  could  very  successfully  he  transported  in  this  stage,  but 
the  importation  of  slightly  larger  caterpillars  indicates  that  the  per- 
centage of  parasitism  would  average  to  be  very  small  at  the  best,  and 
it  is  probable  that  the  best  would  rarely  be  achieved. 


154 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


GIPSY-MOTH  CATERPILLARS,  SECOND  TO  FIFTH  STAGES. 
EUROPEAN  IMPORTATIONS. 

The  first  import  at  ions  of  gipsy-moth  caterpillars  in  the  second  to 
fifth  stages  were  made  in  1907.  Small  wooden  boxes,  each  with  a 
capacity  of  about  40  cubic  inches,  were  used  for  the  purpose,  and 
all  shipments  were  by  mail.  The  caterpillars,  usually  to  the  number 
of  100,  were  inclosed  in  these  boxes,  together  with  seYeral  twigs 
hearing  fresh  foliage. 

The  method  was  of  doubtful  utility,  and  at  the  same  time  no 
improYement  upon  it  could  be  deYised  short  of  cold  storage  en  route. 
On  receipt  the  twigs  would  usually  be  stripped  bare  of  foliage.  Some 
of  the  caterpillars  were  invariably  dead — whether  from  starvation  or 
from  injuries  received  at  the  time  of  collection  or  subsequently  could 
not  be  determined.  The  remaining  caterpillars  were  in  all  stages  of 
emaciation  and  many  of  them,  though  still  living,  were  too  weak  to 
recuperate. 

Parasites  in  considerable  variety  but  always  in  very  small  num- 
bers issued,  for  the  most  part  en  route,  but  occasionally  from  the 
caterpillars  after  receipt.  Nothing  could  be  decided  as  a  result  of 
these  importations  and  their  repetition  was  resolved  upon. 

It  was  planned  to  import  much  larger  numbers  in  190S  without 
modifying  the  methods  employed  the  year  before.  In  this  respect 
success  was  not  achieved,  principally,  it  would  appear,  on  account  of 
the  difficulty  of  collecting  these  small  caterpillars  in  numbers,  espe- 
cially in  localities  where  the  gipsy  moth  was  not  very  abundant. 
Furthermore,  it  became  increasingly  evident  that  the  percentage  of 
parasitism  (so  far  as  it  could  be  determined  by  the  actual  number  of 
parasites  secured)  was  so  insignificant  as  to  make  the  task  of  import- 
ing sufficiently  large  numbers  of  any  one  parasite  for  the  purpose  of 
colonization  wholly  impracticable.  Many  of  the  lots  of  caterpillars 
which  were  received  in  the  best  condition  produced  no  parasites  at 
all.  It  was  therefore  evident  that  if  extensive  operations  in  any 
locality  should  be  determined  upon,  complete  failure  might  result 
through  the  absence  of  the  parasites  in  that  particular  locality  dur- 
ing that  particular  season.  Nothing  less  than  an  improvement  in 
the  service  of  several  thousand  per  cent  over  that  of  1907  or  1908 
would  answer,  and  this  was  altogether  out  of  the  question,  except 
at  an  expenditure  which  even  the  generous  funds  appropriated  by  the 
State  and  Federal  Governments  could  not  cover.  Further  importa- 
tions from  Europe  were  regretfully  decided  to  be  impracticable. 


IMPORTATION'  AND  HANDLING  OF  PARASITE  MATERIAL.  155 


JAP  A  XESE   I MPORTATIO  N  B . 

It  has  already  been  told  how  Prof.  Kincaid  spent  the  summer  of 
1!M)S  in  Japan  in  the  interests  of  the  parasite  work.  While  there,  in 
cooperation  with  the  Japanese  entomologists,  lie  evolved  a  wholly 
new  method  for  the  transportation  of  the  immature  eaterpillars  of 
the  gipsy  moth,  which  would  have  been  applicable  in  the  ease  of 
European  importations  if  it  had  seemed  to  be  worth  while  to  con- 
tinue these  importations  in  190!).  Large  oblong  wooden  boxes  hav- 
ing a  capacity  of  about  H  cubic  feet  were  used.  Like  all  the  boxes 
received  from  Japan,  they  were  most  excellently  constructed  of  a 
sort  of  wood  which  was  less  affected  by  dampness  than  most. 
The  success  of  the  work  was  very  largely  dependent  upon  both  the 
character  of  the  wood  and  the  excellence  of  construction.  It  is  cer- 
tain that  ordinary  packing  boxes  would  have  warped  to  such  an 
extent  as  to  permit  the  escape  of  the  small  caterpillars. 

These  boxes  (see  PI.  V,  fig.  2)  were  first  lined  with  several  thick- 
nesses of  absorbent  paper,  which  was  then  thoroughly  dampened. 
Small  branches  of  a  species  of  Ahnis  were  attached  to  the  sides,  so 
that  the  interior  was  a  mass  of  green  foliage;  the  caterpillars  to  the 
number  of  several  hundred  wore  introduced, the  CO V6T tightly  attached, 
and  the  whole  sent  in  cold  >t  <  >rage  from  Yokohama  to  Boston  with 
scarcely  an  interruption  en  route.  Sometimes  the  ends  of  the 
branches  were  thrust  into  a  piece  of  succulent  root  (radish  or  potato), 
but  this  proved  unnecessary,  and  rather  a  detriment  than  otherwise. 

The  condition  of  these  boxes  on  receipt  was  usually  good,  and  in 
some  instances  surprising.    In  some  of  the  best  of  them  scarcely  a 

leaf  was  withered  or  even  discolored,  and  in  one  in  particular  it 
seemed  almost  as  though  the  branches  had  been  freshly  collected, 
with  the  early  morning  dew  Mill  clinging  to  the  leaves.  This  Illusion 
was  almost  instantly  destroyed,  for  within  an  hour  practically  every 
leaf  had  dropped  from  the  stem  and  was  already  beginning  to  blacken, 
as  though  struck  by  a  sudden  blight. 

There  was  a  good  deal  of  difference  in  the  condition  of  the  cater- 
pillars. Those  which  had  been  shipped  in  the  second  and  third  stages 
almost  invariably  anrived  in  the  best  condition.  There  was  scarcely 
any  mortality  en  route,  and  physically  they  wore  all  in  perfect  health 
and  ready  to  feed  voraciously.  Larger  caterpillars  did  not  survive 
their  journey  so  well,  and  among  those  that  had  reached  the  fifth 
stage  there  was  always  a  heavy  mortality,  and  the  survivors  were 
never  very  healthy  and  would  mostly  die  without  feeding.  It  would 
appear  that  they  were  so  heavy  as  to  be  thrown  to  the  bottom  of  the 
box  while  dormant  through  cold,  and  thus  become  injured. 

While  technically  a  success,  these -attempts  were  practically  fail- 
ures.   Xo  parasites  were  secured  in  anything  more  than  the  most 


156 


PARASITES  OF  GIPSY  AND  BROW N-T ATI,  MOTHS. 


insignificant  numbers,  which  could  not  he  secured  much  more  easily 
in  other  ways,  and  no  further  importations  were  attempted  in  1909. 

Relatively  such  small  quantities  of  this  class  of  material  have  been 
received  as  to  make  unnecessary  any  specialty  devised  methods  for 
their  economical  handling.  With  very 'few  exceptions  the  boxes  were 
opened  immediately  upon  receipt  and  most  carefully  sorted  for  parasites 
and  living  caterpillars.  A  few  of  the  large  Japanese  boxes  were  not 
opened  immediately,  but  holes  were  bored  in  the  end,  cones  and  tubes 
inserted,  and  living  insects  of  all  sorts  thus  attracted  to  the  light  and 
removed.  The  living  caterpillars  were  placed  in  cages  or  trays  and 
fed,  and  occasionally  a  few  parasites  were  thus  secured  in  addition 
to  those  present  in  the  boxes  upon  receipt. 

It  is  very  much  to  be  regretted  that  the  dead  and  dying  cater- 
pillars were  not  preserved  for  subsequent  examination  and  dissection, 
but  it  was  only  in  1909,  after  the  shipments  of  this  sort  of  material 
had  been  discontinued,  that  the  wholesale  dissection  of  caterpillars 
was  attempted  for  the  purpose  of  ascertaining  the  proportion  of 
parasitized  individuals.  At  the  best,  even  after  long  experience,  it  is 
a  tedious  process,  especially  in  the  case  of  material  which  has  been 
killed  and  preserved. 

A  few  caterpillars,  accidentally  imported  in  their  early  stages  with 
Apanteles  cocoons  in  1910,  were  saved  and  dissected  with  good  results 
from  a  technical  standpoint. 

GIPSY-MOTH  CATERPILLARS,  FULL-FED  AND  PUPATING. 

Importations  of  large  caterpillars  (PI.  VI)  ready  or  nearly  ready 
to  pupate  were  first  made  in  1905,  and  it  was  demonstrated  during 
that  year  that  they  could  be  brought  to  America  with  a  fair  degree 
of  success,  and  that  at  least  a  proportion  of  the  parasites  with  which 
they  were  infested  could  be  reared. 

Ever  since  1905  we  have  been  attempting  to  improve  upon  the 
methods  first  used  during  that  year  and  have  experimented  with 
scores  of  modifications  of  the  most  successful,  some  of  which  were 
intentional  while  others  were  incidental  to  the  fact  that  there  have 
been  many  different  collectors,  each  of  whom  has  displayed  some 
individuality  in  his  methods  of  collecting  and  packing.  It  would 
be  tedious  and  is  probably  unnecessary  to  go  into  detailed  de- 
scriptions of  even  a  part  of  these  various  intentional  or  accidental 
experiments. 

The  most  successful  method  yet  devised  involves  the  use  of  rather 
shallow  wooden  boxes  having  a  capacity  of  from  40  to  70  cubic 
inches.  (See  PL  VIII,  fig.  3.)  Quite  a  large  number  of  shipments 
has  been  made  in  much  larger  boxes,  but  their  condition  on  receipt  has 
almost  invariably  been  very  bad.  The  boxes  must  be  tight  to  prevent 
the  escape  of  tachinid  larvae,  which  can  apparently  pass  through  any 


Bui.  91,  Bureau  of  Entomoiogy,  U.  S.  Dept.  of  Agriculture  PLATE  VI. 


Different  Stages  of  the  Gipsy  Moth  (Porthetria  dispar). 

Egg  mass  on  centerof  twig;  female  moth  ovipositing  just  below;  female  moth  below,  at  left, 
enlarged;  male  moth,  somewhat  reduced,  immediately  above;  female  moth  immediately  above, 
somewhat  reduced;  male  moth  with  wings  folded  In  upper  left;  male  chrysalis  at  right  of 
this;  female  chrysalis  again  at  right;  larva  at  center.  (Original.) 


IMPORTATION  AND  HANDLING  OF  PARASITE  MATERIAL.  157 


opening  large  enough  to  accommodate  the  head.  No  special  pro- 
vision for  ventilation  is  necessary,  but  it  is  necessary  to  construct 
the  boxes  of  soft  and  absorbent  wood  in  order  to  secure  best  results. 
This  will  not  only  prevent  too  rapid  evaporation,  but  superfluous 
moisture  will  first  be  absorbed  and  subsequently  will  evaporate. 
Tin  boxes  are  wholly  unsuitable  and  paper  or  pasteboard  have  never 
been  at  all  satisfactory. 

Twigs  with  foliage  should  be  included  in  each  box,  and  these  must 
be  long  enough  to  remain  (irmly  braced  in  case  the  caterpillars  eat 
the  foliage.  Some  very  bad  results  have  followed  the  use  of  loose 
foliage,  a  practice  which  certain  collectors  have  been  persistent  in 
following. 

The  fewer  the  caterpillars  included  in  each  box  the  better  the 
results.  The  number  has  gradually  been  reduced  from  100  at  first 
to  20  during  the  past  few  years.  Undoubtedly  10  would  be  better 
yet.  but  not  enough  better  to  make  the  added  expense  an  economy. 

The  more  nearly  the  caterpillars  are  ready  to  pupate  when  packed 
the  better.  If  collected  just  a  few  days  before  pupation,  they  usually 
arrive  in  good  shape,  provided  conditions  otherwise  are  as  they 
should  be. 

Shipments  by  mail  have  generally  been  successful  when  the  boxes 
wen4  not  smashed,  as  has  BOmetimes  happened,  or  when  something 
else  was  not  wrong.  Shipments  by  express  without  cold  storage 
have  been  equally  successful  when  the  boxes  have  been  properly 
packed.  As  has  been  said,  there  is  no  need  to  provide  for  the  ven- 
tilation of  the  interior  of  the  box,  but  the  exterior  must  be  exposed 
to  the  air  on  at  h-ast  one  side  to  permit  the  evaporation  of  the  mois- 
ture4 absorbed  by  the  wood.  Otherwise,  as  nearly  always  happens, 
when  a  part  of  the  caterpillars  or  pupa1  die,  they  decompose,  and  as  a 
result  of  their  presence 8  similar  fate  usually  overt akes  the  remainder. 
Some  very  large  shipments  were  a  complete  loss  in  1007,  merely 
because  a  European  agent,  prevented  by  newly  enforced  postal 
regulations  from  making  shipments  by  mail,  packed  the  boxes  tightly 
in  largt  packing  cases  and  forwarded  them  by  express.  When  the 
lids  were  removed  from  these  cases  the  sides  of  the  boxes  were  found 
to  be  thoroughly  damp,  and  the  whole  exhaled  an  ammoniac al  odor 
so  strong  that  it  would  seem  of  itself  alone  suflicient  to  destroy  any 
ordinary  form  of  insect  life. 

Bundles  of  boxes  wrapped  in  thick,  glazed  paper  have  almost  invari- 
ably been  received  in  bad  condition.  If  the  paper  is  soft  and  absorbent 
it  is  generally  satisfactory.  One  collector  wrapped  several  packages 
in  a  thick  fabric  composed  of  tarred  paper  strengthened  by  muslin, 
and  the  content-  rotted. 

(  old  storage  in  the  case  of  shipments  of  this  character  would  never 
have  been  either  necessary  or  even  desirable  had  it  not  been  for  the 


158 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


difficulties  experienced  in  the  importation  of  Blepharipa  scutellata. 
All  other  species  of  parasites  could  be  secured  equally  as  well  or  better 
from  shipments  under  normal  conditions,  but  because  Blepharipa 
differed  from  all  the  others  in  this  apparently  minor  characteristic, 
it  was  found  necessary  to  make  use  of  cold  storage  for  practically 
all  of  the  very  large  shipments  made  during  1909  and  1910. 

No  large  shipments  of  full-fed  caterpillars  have  been  made  from 
Japan.  They  were  rendered  unnecessary  in  the  first  place  on  account 
of  the  very  excellent  and  intelligent  service  rendered  by  the  Japanese 
entomologists.  There  are  but  three  important  parasites  to  be  secured 
from  these  large  caterpillars  in  Japan,  and  the  cocoons  and  puparia 
of  these  have  been  reared  and  forwarded  to  us  in  specially  devised 
packages,  with  almost  uniformly  good  results. 

There  have  been  a  few  very  valuable  lots  of  material  of  this  char- 
acter shipped  otherwise  than  as  above  described.  It  is  by  no  means 
certain  that  if  sufficient  time  and  experimentation  were  to  be  devoted 
to  the  subject  some  of  these  occasional  and  successful  modifications 
might  not  be  developed  into  something  better  than  has  yet  been 
tested.  Any  deviation  is  apt  to  prove  disastrous,  however,  as  wit- 
nessed in  1910,  when  failure  resulted  because  the  quality  of  the  paper 
used  for  wrapping  the  bundles  of  boxes  was  changed  in  several  instances 
from  that  employed  at  any  time  previously.  It  is  very  difficult,  and  in 
practice  impossible,  to  foresee  such  minor  contingencies  and  provide 
against  them.  The  really  serious  phase  of  the  situation  lies  in  the 
fact  that  such  a  slight  modification  may  result  not  only  in  the  com- 
plete loss  of  the  shipment  itself,  but  in  a  year's  delay  before  it  can  be 
remedied.  By  the  time  the  first  shipments  are  received  and  the 
trouble  recognized,  it  is  apt  to  be  too  late  to  apply  a  remedy  that 
year,  even  by  the  use  of  the  cable. 

The  laboratory  methods  in  use  for  the  handling  of  the  parasite 
material  of  this  sort  have  been  modified  in  various  ways,  more  espe- 
cially for  the  express  purpose  of  overcoming  the  difficulty  in  hiber- 
nating the  puparia  of  Blepharipa  scutellata.  Such  of  these  modifica- 
tions as  have  been  primarily  made  for  this  special  purpose  will  be 
discussed  in  the  account  of  Blepharipa  which  will  be  found  elsewhere. 

In  general  it  has  been  the  practice  to  open  the  boxes  immediately 
upon  their  receipt,  and  to  sort  the  contents  in  accordance  with  their 
character.  The  tachinid  puparia  were  always  carefully  counted, 
and  of  late  years  they  have  been  sorted  to  a  certain  extent  into 
species. 

Jn  1907  all  the  puparia  were  placed  in  jars,  without  sorting,  with  a 
little  very  slightly  dampened  earth  which  was  kept  from  di  ving  by 
the  use  of  a  wet  sponge.  In  1908  they  were  soiled  to  species,  so  far 
as  this  was  practicable,  and  all  were  kept  dry.  In  J909  the  Blepharipa 
puparia  were  sorted  <>m  and  placed  in  earth  as  soon  thereafter  as 


IMPORTATION  AND   HANDLING  OF   PA  HAS  IT  K   MATKRIAL.  159 


possible.  rrii(*  remainder  were  placed  in  small  tube  cages,  and  taken 
to  the  field  where  they  were  to  be  liberated.  An  attendant  counted 
the  number  of  flies  issuing,  and  watched  for  secondary  parasites. 
Since  no  secondary  parasites  issued  in  the  summer  from  puparia 
secured  in  this  manner,  in  1910  the  puparia  were  merely  placed  in 
caires  which  were  taken  to  the  colony  site  and  left  unattended  until 
the  Hies  had  ceased  to  issue. 

After  the  adults  of  the  summer-issuing  forms  have  all  ceased  to 
emerge,  the  sound  puparia  are  more  or  less  carefully  sorted.  Those 
supposed  to  be  ParasetUjtna  seffreyata,  indistinguishable  externally 
from  dead  Tricholyga  or  Tachina,  are  buried  in  damp  earth  for  the 
winter.  Mr.  .1.  1).  Tothill,  one  of  the  assistants  at  the  laboratory, 
devised  an  ingenious  method  for  separating  the  puparia  containing 
the  healthy  pupa'  of  Parasetigena  from  those4  containing  dead  Tachina 
pr  Tricholyga,  by  holding  them  so  that  they  were  viewed  against  a 
narrow  beam  of  very  strong  light.     The  method  was  not  infallible, 

but  served  its  purpose  fairly  well,  and  was  the  first  of  many  which 

had  been  experimented  with  which  was  at  all  successful. 

The  [iving  caterpillars  removed  from  the  boxes  have  been  placed 
in  cages  or  trays  and  fed,  but  only  an  insignificant  proportion  of  them 

has  ever  lived  long  enough  to  be  killed  by  the  parasites  which  many 
of  t  hem  have  contained.  1  auge  numbers  of  them  have  been  dissected 
for  the  purpose  of  determining  the  proportions  parasitized. 

The  dead  caterpillars  nol  infrequently  contain  the  puparia  of 
Tricholyga,  when  this  parasite  happens  to  be  common  in  the  locality 
from  which  the  shipment  originated.  I'nder  such  circumstances 
they  are  placed  in  tube  cages  for  the  emergence  of  the  Hies.  If 
Tricholyga  is  not  present  in  the  boxes  in  the  form  of  free  puparia  the 
dead  caterpillars  may  as  well  be  discarded,  since  it  is  only  very 
rarely  that  any  other  tachinid  pupates  in  this  manner. 

Pique,  both  living  and  dead,  nearly  always  contain  a  considerable 
number  of  the  larva*  of  Bh  pliari j>a  scutulata.  They  are,  therefore, 
placed  over  damp  earth  in  older  that  the  larva*  may  pupate  under 
natural  conditions.  Other  tachinids  may  occur  in  the  pupa,  but 
never  in  anything  but  insignificant  numbers. 

GIPSY-MOTH 

It  would  seem  as  though  it  ought  to  be  an  easy  matter  to  import 
the  pupa)  (PI.  VI)  of  the  gipsy  moth  in  good  condition,  but  for 
reasons  which  are  not  altogether  clear  in  every  instance  the  vast 
majority  of  the  importations  of  pupa)  have  been  worthless,  or  worse 
than  worthless,  since  the  handling  of  worthless  material  involves  an 
additional  waste  of  labor.  Too  often  the  cause  of  failure  is  directly 
and  obviously  the  result  of  careless  packing,  and  the  number  of  lots 
of  pupa4  which  have  been  received  packed  with  the  care  which  is 


160  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

essential  to  success  is  very  small.  The  most  successful  shipments 
ever  received  were  carefully  packed  in  slightly  dampened  sphagnum 
moss,  so  arranged  that  the  individual  pupae  rarely  touched  each  other. 
One  or  two  successful  importations  thus  received  in  1908  were  used 
as  the  basis  for  future  instructions  to  collectors,  and  in  every  instance 
in  which  the  directions  were  carefully  followed  in  1909  the  results 
were  equally  good.  In  1910  additional  material  apparently  packed 
with  the  same  care  was  received  from  the  same  source  and  via  the 
same  route.  For  no  apparent  reason  whatever  it  was  worthless 
when  received. 

In  consequence  of  this  another  method  which  has  occasionally  been 
followed,  will  be  recommended  for  shipments  in  1911.  This  has 
been  employed  successfully  upon  various  occasions,  although  without 
anything  like  uniform  success,  and  is  in  effect  the  same  as  that  used 
for  the  shipment  of  full-fed  and  pupating  caterpillars  and  the  same 
precautions  must  be  used.  It  will  probably  be  better  to  place  a 
somewhat  larger  quantity  of  foliage  in  the  box  to  prevent  the  pupae 
from  being  thrown  about  too  much  in  transit. 

So  very  few  shipments  of  gipsy-moth  pupae  have  been  received 
at  the  laboratory  as  to  have  rendered  unnecessary  any  special  devices 
for  their  handling  after  receipt.  Each  year  a  few  of  the  lots  of  cater- 
pillars have  contained  a  few  individuals  which  were  collected  as  pre- 
pupae  or  as  pupae,  and  from  such,  an  occasional  parasite  of  one  or 
another  of  the  species  peculiar  to  the  pupae  has  been  reared.  These 
have  been  so  few,  however,  as  to  be  of  entirely  inconsequential  value, 
except  from  a  technical  standpoint. 

The  actual  shipments  of  pupae  collected  as  such  have  been  handled 
exactly  as  though  they  consisted  of  active  caterpillars  which  pupate 
en  route,  with  the  one  difference  that  the  pupa?  received  have  usually 
been  inclosed  in  darkened  cages  with  tubes  attached,  in  order  more 
easily  to  remove  the  parasites  as  they  issued. 

In  1908  pupae  were  received  in  satisfactory  condition  for  the  first 
time  since  the  preliminary  shipments  were  made  in  1905,  and  it  was 
not  until  then  that  the  host  relations  of  several  of  the  parasites, 
notably  Chalcis  spp.  and  Monodontomerus  sereus,  were  finally  deter- 
mined. These  lots  were  studied  with  the  greatest  care,  each  indi- 
vidual pupa  being  opened  on  receipt  and  for  the  most  part  isolated 
in  a  small  vial,  in  order  that  it  might  be  dissected  after  the  contained 
parasite  had  issued . 

BROWN-TAIL  MOTH  EGG  MASSES. 

No  difficulty  has  ever  been  experienced  in  the  importation  of  the 
egg-masses  of  the  brown- tail  moth  (PI.  VII),  except  that  when  cold 
storage  is  not  used  a  portion  of  the  parasites  are  apt  to  hatch, 
and  either  escape  or  die  en  route,    Wooden  boxes  of  various  sizes  and 


Bui.  91,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agriculture.  PLATE  VII. 


Different  Stages  of  the  Brown-tail  Moth  (Euproctis  chrysorrhcea^. 

Winter  nest  at  upper  left:  male  and  female  adults,  lower  right;  another  winter  nest,  upper  right: 
male  and  female  chrysalides  above,  maleatleft;  full-grown  larva  in  center,  somewhat  reduced: 
young  larva-  at  its  left;  egg  mass,  the  eggs  hatching,  at  lower  left;  female  ovipositing  on  leaf; 
egg  mass  also  on  same  leaf,    (original.  | 


IMPORTATION  AND  HANDLING  OF  PARASITE  MATERIAL.  161 


construction  have  been  employed  with  uniformly  good  results,  and 
nearly  all  shipments  have  been  made  by  mail.  All  of  the  parasites 
have  been  found  amenable  to  methods  of  laboratory  control,  and 
their  reproduction  has  been  undertaken  as  an  economic  venture  in 
each  instance.  Under  such  circumstances  there  is  no  need  to  import 
large  quantities  except  for  the  purpose  of  discovering  other  forms  of 
parasites,  should  they  exist. 

HIBERNATING  NESTS  OF  THE  BROWN-TAIL  MOTH. 

The  importation  of  hibernating  nests  (PI.  VII)  of  the  brown-tail 
moth  has  been  attended  with  very  good  success,  as  a  rule,  but  b\r  no 
means  invariably.  If  they  are  sent  too  early  in  the  winter  and  sub- 
jected to  long  continued  high  temperature  before  shipment,  or  while 
in  transit,  the  caterpillars  will  die  instead  of  resuming  activity  in  the 
spring. 

If  sent  too  late  in  the  spring,  exposure  to  abnormally  high  temper- 
atures en  route  results  in  premature  activity  of  the  caterpillars  and 
they  will  arrive  in  had  and  sometimes  in  worthless  condition. 

If  sent  in  the  middle  of  the  winter  they  will  be  very  nearly  ready 
to  resume  activity  on  receipt,  but  if  again  exposed  to  cold  they  will 
become  dormant  and  remain  so  until  about  the  time  when  they  would 
normally  have  become  active.  This  seems  not  too  prejudicial  to 
them,  if  one  is  to  judge  by  their  activities  during  the  fust  few  weeks 
after  the  resumption  of  activity,  but  in  >ome  subtle  manner  a  change 
has  been  wrought,  and  they  do  not  commonly  go  through  to  success- 
ful pupation.  Thi>  phenomenon,  previously  observed  with  other 
insects,  is  discussed  at  some  length  in  the  account  of  the  tachinid 
Zygobothria  nidicola,  which  hibernates  within  the  caterpillars,  but 
which  does  not  destroy  its  host  until  after  it  has  spun  for  pupation. 

The  failure  to  rear  these  caterpillars  beyond  a  certain  stage  in  the 
spring  was  at  first  attributed  to  some  fault  in  the  methods  employed, 
and  when  it  was  finally  apparent  that  the  fault  lav  elsewhere  there 
was  no  longer  need  to  seek  to  remedy  it.  The  one  parasite  desired 
was  found  to  be  already  introduced  and  apparently  well  established 
as  the  result  of  a  colonization  some  three  years  before. 

The  methods  for  handling  the  imported  nests  have  varied  from 
season  to  season  in  accordance  with  the  habits  of  the  parasites  which 
it  was  desired  to  rear  from  them.  These  methods  will  be  more  fully 
described  in  the  discussions  of  the  several  parasites  involved:  Ptero- 
malus  egregius,  A  pantiles  htcteicolor,  and  Zggobothria  nidicola. 

IMMATURE  CATEBPELLABS  OF  THE   BROWN-TAIL  MOTH. 

Taken  all  together,  importations  of  active  brown-tail  caterpillars 
(PI.  VII)  in  the  second  to  fourth  spring  stages  aggregate  a  con- 
siderable number.    These  importations  were  undertaken  on  the 
05077°— Bull.  91—11  11 


162  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

supposition  that  there  were  parasites  which  attacked  them  as  soon 
as  they  resumed  activity  in  the  spring,  and  left  them  before  they 
reached  their  last  stage.  There  are,  indeed,  several  species  which 
have  such  habits,  but  there  is  none  amongst  them  which  may  not  be 
secured  equally  well  from  either  the  hibernating  caterpillars  or  from 
the  full-fed  and  pupating  caterpillars,  or  from  both.  In  consequence 
the  importation  of  partly  grown  caterpillars  in  the  spring  has  never 
been  attempted  except  experimentally. 

Of  the  considerable  number  which  has  been  received,  nearly  all 
have  been  packed  in  the  same  manner  as  are  the  full-fed  caterpillars. 
They  are  nearly  always  alive  on  receipt,  and  usually  feed  voraciously 
when  given  an  opportunity.  Undoubtedly  a  considerable  percentage 
contains  parasites  of  those  species  which  only  emerge  after  the  cocoon 
is  spun,  but  every  attempt  to  rear  these  parasites  by  feeding  the  cat- 
erpillars has  resulted  in  failure.  They  will  feed  once,  at  Jeast,  but 
usually  not  more  than  a  few  times,  and  then  die  sooner  than  would 
have  been  the  case  had  they  not  fed  at  all.  Some  among  them  will 
live  for  a  long  time,  feeding  a  little  but  scarcely  growing  at  all,  and 
sometimes  a  very  small  percentage  will  complete  growth  and  pupate. 
The  percentage  is  so  very  small,  however,  and  the  labor  and  pain  of 
handling  the  caterpillars  is  so  great,  as  to  render  the  work  of  feeding 
them  of  much  more  than  doubtful  economy,  in  every  instance  in 
which  it  has  been  attempted. 

FULL-FED  AND  PUPATING  CATERPILLARS  OF  THE  BROWN-TAIL  MOTH. 

The  temptation  is  strong  to  use  the  present  opportunity  for  the 
purpose  of  giving  vent  to  certain  poorly  suppressed  and  heartfelt 
expressions  of  opinion  concerning  the  infliction  known  euphemisti- 
cally and  very  inadequately  as  the  browm-tail  "rash."  It  is  a  very 
living  subject  of  discussion  during  most  of  the  year  at  the  laboratory, 
but  never  more  so  than  while  the  boxes  of  full-fed  and  pupating 
brown-tail  caterpillars  are  being  received  from  Europe. 

Aside  from  the  fact  that  the  handling  of  this  sort  of  parasite  mate- 
rial has  been  productive  of  most  acute  physical  anguish,  it  lias  been 
altogether  the  most  uniformly  satisfactory  of  any  received.  No  mod- 
ifications in  the  methods  of  packing  have  been  suggested  during  the 
past  five  years,  other  than  a  slight  modification  in  the  form  of  the  box 
in  order  to  alleviate  the  trouble  to  which  reference  is  made  above. 

Rather  shallow  boxes,  having  a  capacity  of  about  50  cubic  inches, 
are  used  for  the  purpose.  (See  PI.  VIII,  figs.  1,  2.)  The  caterpillars 
are  collected,  preferably  just  before  they  spin  their  cocoons,  and  100 
are  placed  in  each  box,  together  with  a  few  twigs  with  foliage  at- 
tached, which  serve  less  as  food  than  as  a  support  for  the  cocoons. 
When  collected  at  the  proper  time  practically  all  will  spin  and  pupate 


IMPORTATION    AND    1 1  AN  DLI  N(i   OF    PAKASITK    MATKPJAL.  163 


en  route,  and  the  cocoons  are  so  strong  as  to  prevent  the  pupa'  from 
becoming  injured. 

There  has  never  been  any  trouble  experienced  through  these  boxes 
sweating  en  route,  as  has  so  frequently  happened  when  boxes  con- 
taining gipsy-moth  caterpillars  have  been  too  closely  confined  in  box 
or  bundle,  but  at  the  same  time  those  which  have  been  exposed  to 
free  circulation  exteriorly  are  noticeably  in  better  condition  than 
others. 

Much  the  larger  proportion  of  the  material  of  tins  sort  has  been 
received  in  perfect  condition  at  the  laboratory,  and  large  quantities 
of  parasites  have  been  reared  from  nearly  every  lot  thus  received. 
Occasionally  boxes  have  been  used  which  were  not  sufficiently  tight 
to  prevent  the  escape  of  the  tachinid  larva\  and  some  loss  has  accrued 
in  consequence.  In  a  number  of  instances  tin4  boxes  have  beeD 
infected  with  fungous  disease,  and  all  or  nearly  all  of  the  caterpillars 
or  freshly  formed  pupa1  have*  died  in  consequence.  In  lather  an 
unnecessary  number  of  instances,  or  bo  it  would  seem,  caterpillars 
have  been  collected  too  young,  and  have  failed  to  pupate  en  route. 
Such  shipments  properly  fall  in  the  class  laM  mentioned,  and  are 
worthless  for  the  purposes  desired. 

Through  a  misunderstanding  nearly  all  of  this  class  of  material, 
was  sent  in  cold  storage  in  1909,  with  the  result  that  the  caterpillars 
failed  t<»  pupate  60  route,  as  would  have  been  t  be  result  otherwise, 
and  a  good  many  of  them  failed  to  pupate  after  receipt.  Considera- 
ble loss  resulted  on  1 1 » i  —  account  before  the  collectors  could  be  noti- 
fied to  return  to  the  original  method  of  shipping  by  mail. 

In  handling  the  DOXCS  of  caterpillars  and  pupa\  a  variety  of  meth- 
ods has  been  employed,  of  which  the  most  satisfactory  appears  to  be 
simply  boring  a  hole  in  the  one  end.  and  introducing  a  paper  cone 
and  tube.  Even  the  removal  of  the  covers  from  a  do/en  or  more 
boxes  without  protection  is  accompanied  by  painful  results,  and 
owing  to  the  difficulty  of  boring  the  holes  without  splitting  the  wood, 
after  the  box  has  been  received  at  the  laboratory,  collectors  are  now 
instructed  to  prepare  the  boxes  for  the  reception  of  the  tube  at  the 
time  of  their  manufacture. 

In  1906  and  1907,  when  the  first  shipments  of  this  character  were 
received,  and  when  little  was  known  of  the  character  of  the  parasites 
which  were  likely  to  be  reared  from  them,  it  was  thought  necessary 
not  only  to  open  each  box,  but  to  sort  it  over,  and  remove  the  tachi- 
nid puparia  which  were  always  present  in  a  larger  or  smaller  number. 
It  was  known  that  there  were  always  present  certain  species  of  tachi- 
nids  which  would  only  complete  their  final  transformations  success- 
fully when  their  puparia  were  kept  more  or  less  moist,  and  it  was 
expected  that  among  the  parasites  of  the  brown-tail  moth  would  be 
some  possessing  this  characteristic.    Opening. the  boxes  without  some 


164 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


sort  of  protection  was  utterly  impossible.  Automobile  goggles  were 
used  to  protect  the  eyes,  various  forms  of  respirators  to  prevent  the 
inhalation  of  the  spines,  the  hands  were  protected  by  rubber  gloves, 
and  the  neck  and  face  were  swathed  in  accordance  with  the  fancy 
of  the  operator. 

Two  ingenious  types  of  headdress  (PL  IX,  fig.  1)  were  devised  by 
Mr.  E.  S.  G.  Titus  in  the  hope  that  they  would  solve  the  difficult}', 
but  it  was  found  that  they  were  not  only  unbearably  hot,  but  that 
the  glass  fronts  would  quickly  become  covered  with  moisture  which 
could  not  be  removed. 

In  1907  a  much  larger  quantity  of  this  sort  of  material  was  received 
than  during  the  previous  summer,  and  it  was  practically  a  necessity 
that  some  method  be  devised  which  would  do  away  with  at  least  part 
of  the  trouble.  After  some  little  experimentation  the  arrangement 
shown  in  the  illustration  was  the  result.  (PI.  IX,  fig.  2.)  It  con- 
sisted of  an  ordinary  show  case,  with  sides  and  top  of  glass  and  with 
a  wooden  slide  in  the  back.  The  two  ends  were  removed  and  re- 
placed with  boards  in  which  armholes  had  been  cut.  Thick  canvas 
sleeves  were  attached  to  these,  through  which  the  gloved  .hands  of 
the  operator  were  thrust,  and  it  was  found  that  the  work  could  be 
done  with  what  was,  comparatively  speaking,  a  minimum  of  dis- 
comfort and  danger. 

In  1908,  for  several  reasons  which  need  not  be  entered  into  here, 
it  was  thought  desirable  to  discontinue,  temporarily,  the  importation 
of  large  quantities  of  the  pupating  caterpillars,  and  it  was  also  demon- 
strated that  all  of  the  parasites  which  were  secured  from  them  would 
complete  their  transformations  without  being  kept  moist.  The  work 
of  sorting  over  the  boxes  of  parasite  material  was  thus  demonstrated 
to  be  unnecessary,  and,  consequently,  in  1909,  when  large  importa- 
tions were  resumed,  the  covers  were  simply  removed  from  the  boxes, 
which  were  then  stacked  up  in  the  large  wooden  tube  cages  (PL  X, 
fig.  1),  which  had  originally  been  constructed  for  the  rearing  of 
parasites  from  the  imported  hibernating  nests. 

BROWN-TAIL  MOTH  PUP.E. 

Several  attempts  have  been  made  to  ship  the  pupae  (PL  VII) 
of  the  brown-tail  moth,  packed  in  moss,  as  was  at  one  time  rec- 
ommended for  the  shipment  of  the  pupae  of  the  gipsy  moth.  Such 
attempts  have  usually  been  more  or  less  satisfactory,  but  never  as 
satisfactory  as  when  the  cocoons  were  collected  in  the  field  and  placed 
loose  in  the  boxes  together  with  the  active  caterpillars.  If  only  a 
small  portion  of  the  pupae  is  collected  in  the  field,  the  only  sure  method 
of  detecting  their  presence  is  by  the  occurrence  of  the  pupal  parasites 


Bui.  91,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agriculture, 


Plate  VIII. 


Fiq.  3.— Boxes  Used  in  Shipping  Caterpillars  of  the  Gipsy  and  Brown-Tail 
Moths  by  Mail.  (Original.) 


Bui.  91,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agriculture, 


Plate  IX. 


Fig.  2.— Show  Case  Used  When  Opening  Boxes  of  Brown-Tail  Moth  Cater- 
pillars Received  from  Abroad.  (Original.) 


Bui.  91,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agriculture.  PLATE  X. 


Fig.  1.— Large  Tube-Cage  First  Used  for  Rearing  Parasites 
from  Imported  Brown-Tail  Moth  Nests  and  Latterly  for 
Various  Purposes.  'Original.) 


Fig.  2.— Method  of  Packing  Calosoma  Beetles  for  Shipmemt.  (Original.) 


IMPORTATION  AND  HANDLING  OF  PARASITE  MATERIAL.  165 


among  those  roared.  A  large  number  of  the  shipments  has  produced 
small  or  large  percentages  of  these  parasites. 

Shipments  of  pupa?  collected  as  such  would  preferably  be  made  in 
cold  storage.  The  most  of  the  parasites,  including  those  which  are 
or  which  appear  to  be  of  the  most  importance,  emerge  coincidently 
or  nearly  so  with  the  moths  themselves,  and  if  sent  by  ordinary  mail 
they  are  apt  to  issue  and  die  en  route. 

COCOONS  OF  HTMENOPTEROUS  PARASITES. 

There  is  only  one  hymenopteroua  parasite  of  demonstrated  impor- 
tance which  nt  tacks  the  gipsy  moth,  and  which  --pins  a  cocoon  outside 
of  the  host.  This  is  ApanUUsfulvipes,  of  Europe  and  Japan,  and  it  is 
probable  that  the  numbers  of  its  cocoons  imported  as  such  have 
amounted  to  at  least  1,000,000. 

Little  care  is  necessary  in  packing  these  for  shipment,  other  than 
that  they  must  not  be  crushed,  nor  yet  too  damp.  A  considerable 
degree  of  dampness  has  been  sustained  without  injury,  but  upon  one 
occasion  in  which  they  were  packed  between  sheets  of  damp  blotting 
paper,  there  was  sufficient  moisture  present  to  thoroughly  soak  the 
cotton  and  some  lo>s  resulted. 

The  Japanese  have  displayed  no  little  ingenuity  in  devising  new 
methods  for  sending  these,  and  with  one  exception,  just  noted,  all 
have  been  good  so  far  as  packing  was  concerned.  One  method, 
which  possessed  a  certain  advantage  over  the  others  in  permitting 
the  adults  which  chanced  to  emerge  en  route  a  certain  amount  of  very 
advantageous  freedom,  was  used  in  a  single  shipment,  which,  partly 
on  that  account  but  principally  on  others,  ranks  as  immeasurably 
the  best  ever  received.  The  cocoons,  to  the  number  of  about  1,000, 
were  inclosed  in  a  little  wicker  cage,  which  in  turn  was  inclosed  in  an 
envelope  of  mosquito  netting  which  prevented  the  cocoons  from  scat- 
tering out,  but  did  not  hinder  the  escape  of  the  adults.  This  cage 
was  supported  in  the  very  center  of  a  Large,  otherwise  empty  wooden 
box  by  means  of  strings  which  were  passed  through  screw  eyes  in  the 
middle  of  each  side  and  drawn  taut.  There  was  nothing  loose  in  the 
box  to  crush  the  delicate  parasites,  no  matter  how  roughly  it  was 
handled,  and  they  were  not  only  given  ample  space  to  expand  and 
stretch  their  wings,  but  they  were  kept  inactive  by  the  perfect  dark- 
ness (or  at  least  were  presumably  so).  It  would  be  a  simple  matter 
to  spray  a  portion  of  one  side  of  the  box  with  a  very  fine  dew  of 
honey,  and  if  this  were  done  the  life  of  the  adults  would  probably 
be  considerably  prolonged. 

Cold  storage  is  an  absolute  necessity  if  the  cocoons  of  this  parasite 
are  to  be  as  much  as  a  week  en  route.    The  transformations  are  apt 


166 


PARASITES  OF  GIPSY  AND  BROWN -TAIL  MOTHS. 


to  be  concluded  in  considerably  less  than  one  week  after  the  spinning 
of  the  cocoon  if  the  weather  is  hot,  and  ever,  under  the  best  of  con- 
ditions which  can  be  devised  for  keeping  them  alive  the  mortality  is 
heavy.  Even  in  the  ordinary  temperature  of  a  steamship's  cold 
room  development  continues.  . 

TACHINID  PUPARIA. 

The  importation  of  tachinid  pup  aria  is  by  no  means  so  simple  as 
the  importation  of  Apanteles  cocoons,  but  at  the  same  time  it  is  easy 
as  compared  with  the  difficulties  attending  the  importation  of  live 
gipsy-moth  caterpillars  from  which  to  rear  these  puparia  in  America. 

In  all,  quite  large  numbers  have  been  received  from  both  Europe 
and  Japan.  A  variety  of  methods  has  been  tested  in  the  hope  of  hit- 
ting upon  one  that  would  be  applicable  for  the  purpose.  Shipping 
in  damp  earth  was  early  attempted,  and  seems  to  be  the  very  first 
method  which  suggests  itself  to  anyone  wishing  to  ship  a  quantity 
of  them,  but  of  all  ways  it  is  very  nearly  the  worst."  It  would  prob- 
ably be  the  best,  if  the  larvae  could  be  allowed  to  enter  the  earth 
naturally  and  if  they  were  left  there  wholly  undisturbed  throughout 
the  time  they  were  in  transit,  but  mingled  with  damp  earth  and 
placed  in  a  box  to  be  sent  by  mail  or  express,  disaster  is  pretty  sure 
to  result.  Cotton  has  also  been  used  several  times,  and  it  is  usually 
as  bad  and  sometimes  worse.  With  the  exception  of  excelsior,  cot- 
ton is  about  the  worst  packing  for  living  insects  that  has  come  under 
observation  at  the  laboratory,  although  gritty  moss,  of  a  sort  which 
dries  brittle,  is  also  bad.  Presumably  there  are  other  worse  sub- 
stances, but  they  have  not  been  discovered  at  first  hand. 

Probably  the  best  packing  material  is  slightly  damp  and  preferably 
living  sphagnum  moss.  The  live  moss  retains  its  moisture  in  a  man- 
ner wholly  different  from  the  moss  which  has  been  killed,  dried,  and 
subsequently  dampened.  Test  shipments,  which  were  sent  to  France 
and  back  without  being  opened,  returned  to  the  laboratory  in  good 
and  almost  unaltered  condition,  in  the  case  of  those  which  were 
inclosed  in  tight  boxes.  Even  when  fully  exposed  to  the  air  the  liv- 
ing moss  seems  to  dry  much  more  slowly  and  to  hold  its  moisture 
more  naturally.  Sphagnum  possesses  the  great  additional  advan- 
tage  of  being  much  softer  when  dry  than  most  other  kinds  of  moss. 

One  disadvantage  attending  the  shipment  of  puparia,  no  matter 
how  they  are  packed,  is  that  of  secondary  parasites.  A  single  colony 
of  Dibrachys,  issuing  en  route  from  one  of  a  lot  of  puparia,  will  result 
in  the  parasitism  of  a  Large  proportion  of  the  remainder.  This 
might  possibly  be  prevented  by  packing  in  sand  or  earth,  but  this 
appears  to  be  about  the  only  advantage  possessed  by  that  method. 

The  puparia  of  certain  tachinids  must-  be  kept  damp,  but  this  is  not 
at  all  necessary  in  the  case  of  all.    Methods  of  packing  and  shipment 


QUANTITY  OF  PARASITE   MATERIAL  IMPORTED. 


167 


will  depend  upon  the  characteristics  of  the  particular  species  under 
consideration.  So  far  as  known,  no  tachinid  which  forms  a  free 
puparium  outside  of  its  host  is  injured  by  exposure  to  moisture. 

The  pupa]  period  of  the  majority  of  the  tachinid  parasites  of  the 
gipsy  moth  and  the  brown-tail  moth  is  quite  short,  usually  lasting 
less  than  two  weeks.  It  is  therefore  necessary  to  make  use  of  cold 
Btorage  en  route,  in  order  to  make  certain  that  the  adults  will  not 
hatch  before  arrival.  By  far  the  larger  part  of  the  puparia  which 
have  been  receive* I  at  the  laboratory  have  thus  hatched,  except  when 
they  were  of  species  which  naturally  hibernated  unless  they  were 
shipped  in  cold  storage. 

CALOSOMA  AM)  OTHER  PREDAGEOUS  BEETLES. 

Quite  a  variety  of  the.  large  carabid  beetles  has  been  imported  from 
abroad  for  experimentation  as  to  their  serviceability  as  enemies  of 
the  gip>y  moth,  or  for  liberation  in  tin*  field  after  this  point  had  been 
demonstrated  satisfactorily.  At  first  some  difficulty  was  experi- 
enced in  accomplishing  their  importation  successfully,  but  later  it 
Was  found  to  be  a  simple  matter  if  proper  care  was  used  in  packing. 
The  great  majority  of  them  have  come  in  ordinary  safety-match  boxes 
(PI.  X.  fig.  2),  each  bos  containing  one  beetle  and  a  wisp  of  sphagnum 
ninss.  I'siiallv  one  or  two  caterpillars  or  other  sort  of  succulent 
inftfvt  have  been  included  for  the  purpose  of  lunch  en  route,  but  the 
practice  is  of  rather  doubtful  value  in  the  case  of  those  species  which 
have  been  handled  in  the  largest  numbers  in  the  laboratory.  Should 
the  beetle  n<>t  fancy  the  quality  of  the  sustenance  provided,  or  refuse 
to  eat  for  any  other  reason,  death  and  decomposition  of  the  victim 
may  result  disastrously  and  be  prejudicial  to  the  health  of  the  beetle. 

These  small  match  boxes  have  been  packed  in  larger  wooden  boxes 
and  sent  through  the  ordinary  mails  with  little  loss  of  life.  Other 
small  wooden  or  paper  boxes  have  similarly  been  used  with  equal 
success. 

Cold  storage  has  occasionally  been  employed  in  a  few  minor  ship- 
ments from  Europe  with  very  good  results.  In  1010  a  large  ship- 
ment of  living  beetles  was  received  in  cold  storage  from  Japan  in 
most  excellent  condition. 

QUANTITY  OF  PARASITE  MATERIAL  IMPORTED. 

In  Mr.  Kirkland's  first  report  as  superintendent  for  suppressing  the 
gipsy  moth  and  the  brown-tail  moth  in  Massachusetts,  several  pages 
were  devoted  to  a  detailed  account  of  each  shipment  of  parasite 
material  received  from  abroad.  After  the  first  year  no  attempt  to 
continue  this  pracl  ice  w  as  made,  and  if  it  were  now  attempted  to  treat 
each  separate  shipment  with  the  same  attention  to  detail,  several 
hundred  additional  pages  would  be  required. 


168 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Accordingly,  in  order  that  at  least  a  rough  idea  of  the  quantity  of 
material  handled  at  the  laboratory  may  be  had,  Table  VII,  which, 
without  being  absolutely  accurate,  is  very  approximately  so,  has 
been  prepared  by  Mr.  R.  Wooldridge,  an  assistant  at  the  laboratory. 


Table  VII. —  Table  showing  number  of  boxes  received  at  the  laboratonj  since  beginning 

of  work. 


1905 

1906 

1907 

1908 

1909 

1910 

Porthetria  dispar  egg  masses  boxes. . 

Porthetria  dispar  larvae  and  puprc  do  

Euproctis  chrysorrhoea  egg  masses  do  

Euproctis  chrvsorrhoea  webs  webs. . 

Euproctis  chrysorrhoea  Larv;r  and  pupae  boxes. . 

Apanteles  fulvipes  and  Apanteles  lacteicolor.  .do 

131 

1 

923 
46 

117,259 
313 

1 

1,539 
87 
55,082 
1,159 

18 
307 
17 

32,830 
160 
13 

32 
8,391 
1 

29,295 
1,167 
21 

1 

5,956 
0 

29,696 
381 
63 

LOCALITIES  FROM  WHICH  THE  PARASITE  MATERIAL  HAS  BEEN 

RECEIVED. 

Mr.  Wooldridge  has  also  prepared  the  accompanying  map  (fig.  1 1) 
showing  the  various  localities  from  which  parasite  material  has  been 
received  each  year  from  1905  to  1910,  inclusive.  It  will  indicate 
the  thoroughness  with  which  the  more  accessible  parts  of  the  world 
have  been  searched  for  parasites  of  these  pests. 

THE  EGG  PARASITES  OF  THE  GIPSY  MOTH. 

Anastatus  bifasciatus  Fonsc. 

The  first  individuals  of  this  species  (fig.  12,  female)  were  reared 
at  the  laboratory  in  the  spring  of  1908  from  eggs  imported  the  pre- 
vious winter  from  Europe  and  Japan.  The  dissimilar  sexes  were  not 
immediately  recognized  as  of  the  same  species,  and  for  a  few  days 
there  was  some  doubt  as  to  whether  one,  two,  or  four  were  represented 
among  the  few  scattering  specimens  emerging.  The  number  was 
soon  reduced  to  two  through  the  obvious  attraction  between  the 
sexes,  and  soon  after  to  the  one,  when  the  senior  author  had  an 
opportunity  to  examine  and  compare  series  from  European  and 
Japanese  sources. 

Their  issuance  had  been  anticipated  a  long  time  before,  and  a 
quantity  of  gipsy-moth  eggs  had  been  collected  in  the  summer, 
before  embryonic  development  had  progressed  beyond  its  initial 
stages,  and  placed  in  cold  storage.  It  was  thought  possible  that 
some  species  of  parasite  might  be  reared  from  imported  eggs  during 
the  fall  or  winter  which  habitually  and  necessarily  oviposited  in  unde- 
veloped eggs,  and  il  was  hoped  thai  those  collected  in  the  summer 
might  be  kept  fresh  enough  to  serve  as  host  material  for  laboratory 
reproduction. 


170  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


As  soon  as  females  of  Anastatus  were  secured,  some  of  these  eggs 
were  removed  from  storage  and  found  to  be  dead,  with  the  contents 
partially  decomposed.  Nevertheless  an  attempt  was  made  to  use 
them,  and  the  parasites  were  given  their  choice  between  them  and 
others  which  contained  embryonic  caterpillars. 

A  few  days  after  their  emergence  the  females  began  to  betray  an 
interest  in  both  sorts  of  eggs,  and  were  several  times  observed  in  the 
act  of  oviposition  or  attempted  oviposition.  Apparently  this  was 
successfully  accomplished,  but  without  further  results,  for  no  second 
generation  resulted.  The  experiment  served  one  purpose,  however, 
in  indicating  beyond  reasonable  doubt  that  the  insect  actually  was  a 
parasite  upon  the  eggs  of  the  gipsy  moth,  and  not  upon  any  chance 
form  of  insect  life  accidentally  included.1 


Fig.  12. — Anastatus  bifasciatus:  Adult  female.    Greatly  enlarged.    (From  Howard.) 


The  exposure  of  the  imported  eggs  to  warmth  for  the  purpose  of 
hastening  the  emergence  of  any  parasites  which  they  chanced  to  con- 

1  How  great  is  the  likelihood  of  error  when  parasites  are  reared  from  unbroken  egg  masses  has  several 
limes  been  Remonstrated  in  the  course  of  the  investigations  and  rearing  work  at  the  laboratory.  Upon 
several  occasions  small  Lepidoptera  have  been  reared  from  egg  masses,  and  more  than  once  their  para- 
sitized pupa'  have  been  found.  Eggs  of  other  species  of  insects,  and  occasionally  parasitized  scale  insects, 
have  also  been  found  attached  to  bits  of  bark  to  which  egg  masses  were  attached.  Very  frequently  cocoons 
of  A  pantclcs  fulvipcs  are  found,  wholly  or  partially  covered  by  the  egg  mass,  and  from  them  several  species 
of  hibernating  secondaries  have  been  reared.  There  is  a  record  of  a  minute  eulophid,  allied  to  Kntedon, 
having  issued  from  a  small  lot  of  eggs  which  had  been  separated  from  nearly  every  trace  of  foreign  matter. 
It  was  thought  then  and  is  still  believed  that  these  came  from  the  eggs  themselves,  and  that  they  were 
actually  parasitic  upon  cither  Anastatus  or  Schedius,  but  when  the  material  from  which  they  issued  was 
examined  two  or  three  cocoons  of  A  pantelcs fulvipcs  were  found  mingled  with  it,  and  what  might  otherwise 
have  been  a  clear  record  was  spoiled. 

There  is  in  Japan  a  limaeodid  molh—J'arasa  sinica  Moore  (hilarula  Staud),  as  determined  by  Dr.  H.  G. 
Dyar— which  appears  habitually  to  seek  out  the  gipsy-moth  egg  masses  as  a  site  for  pupation.  The  larva 
buries  Itself  in  the  mass  before  spinning  Its  OOCOOn,  and  from  outward  appearances  its  presence  is  hardly 
noticeable.  More  than  25  of  these  moths  have  been  reared  under  these  circumstances  from  imported  egg 
masses,  or  their  cocoons  have  heen  found  and  destroyed. 


ECC.  PARASITES  OF  THE  GTPSY  MOTH. 


171 


tain  in  the  hope  that  laboratory  reproduction  could  be  secured  was 
boos  recognized  to  be  a  mistake,  and  as  the  Anastatus  continued  to 
emerge  considerably  ahead  of  the  time  when  they  would  obviously 
have  issued  under  more  natural  conditions,  it  was  resolved  to  remedy 
the  evil,  if  possible,  by  placing  the  parasitized  material  in  cold  stor- 
age. This  experiment  was  successful.  The  further 
transformations  <>f  the  parasites  were  retarded 
without  any  apparent  prejudicial  effects  upon 
their  vitality,  and  in  July  some  .">()()  were  reared 
and  colonized  in  the  field. 


Coincidently  with  the  height  of  their  emergenc 


ig.  13. — A  ntutatua  hi/a.?- 
ciatus;  Uterine  egg. 
Greatly  enlarged. 
(Original.) 


)f  a  small  black 


Issued,  an< 
secondary. 

invest  igati 


FlG.  H.—Anaxtattus    bi/asciatus:    1 1  iivoniai  niu' 
larva.   Greatly  enlarged.  (Original.) 


and  subsequent  to  its  close,  a  considerable  number 
eneyrtid,  later  described  by  the  senior  author  as  Tyndarichus  navse, 
11  were  destroyed  on  the  supposition  that  they  might  be 
Phis  was  not  by  any  mean-;  certain,  and  it  was  resolved  to 
Leir  habits  thoroughly  so  soon  as  opportunity  should  offer. 

Accordingly,  in  the  fall  of  1008, 

following  the  receipt  of  several  con- 
siderable shipments  of  egg  masses 
from  Japan,  an  exhaustive  investi- 
gation of  the  gipsy-moth  egg  para- 
sites was  inaugurated.  These  in- 
vestigations were  more  intimately 

associated  with  the  work  upon 
Schedius,  and  more  will  be  said 
of  them  in  the  discussion  of  that 
species.  So  far  as  Anastatus  was 
concerned,    its    life    and  probable 

habits  stood  revealed  from  the  start.  Almost  in  the  beginning  its 
lar\a>  were  found  (fig.  L4)  and  identified  correctly,  as  was  later 
proved.  They  were  almost  invariably  found  in  eggs  which  had 
been  destroyed  before  embryonic  development  had  taken  place, 

which  showed  conclusively  that  these  eirirs  were  attacked  within  a 
Very  short  time  after  their  dep- 
osition. It  was  known  that  the 
adults  did  not  issue  until  after 
the  caterpillars  had  hatched  from 
healthy  eggs  in  the  spring,  and 
the  fact  that  the  species  was 
single  brooded,  with  a  life  cycle 
that  was  correlated  perfectly  with 
that  of  the  gipsy  moth,  was  as 
certainly  evident  then  as  now,  after  two  years'  observation  of  its 
progress  in  the  field  has  given  ample  confirmation. 

The  egg  of  Anastatus  has  not  been  seen  after  deposition,  but  its 
appearance  before  is  indicated  by  figure  13.    The  full-fed  larva 


Fig.  15. — Anastatus  bifa.scintns:  Pupa  from  gipsy- 
mothegg.   Greatly  enlarged.  (Original.) 


172 


PARASITES  OF  GIPSY  AND  BROWX-TAlL  MOTHS. 


removed  from  host  egg  is  well  represented  by  figure  14,  and  the 
pupa  by  figure  15.  This  latter  is  very  beautifully  colored,  the 
creamy  ground  color  being  set  off  by  darker  abdominal  bands  and 
wing  covers,  and  by  the  delicately  tinted  reddish  eyes. 

It  was  soon  demonstrated  by  a  careful  study  of  the  European 
eggs  that  no  other  parasite  and  no  secondaries  were  present.  These 
eggs  were  therefore  kept  in  confinement  until  after  the  caterpillars 
had  all  hatched  in  the  spring.  Then  those  which  remained  were 
examined,  and  the  number  which  contained  parasites  carefully  esti- 
mated, and  found  to  be  about  80,000,  nearly  all  of  which  were  con- 
tained in  a  very  large  shipment  received  during  the  winter  through 
Prof.  Jablonowski,  and  collected  from  various  Hungarian  localities. 

The  Japanese  eggs,  which  contained  numerous  secondary  parasites 
as  well  as  Anastatus,  were  all  carefully  rubbed  clear  of  their  hairy 
covering,  and  those  which  contained  Anastatus  larvae  (PI.  XI,  fig.  2) 
carefully  and  painstakingly  picked  out  by  hand,  one  by  one.  In 
this  manner  enough  to  make  a  total  of  nearly  90,000  of  the  para- 
sites were  secured. 

'One  exceedingly  important  characteristic  of  the  parasite  was  not 
considered  with  sufficient  attention  at  a  time  when  this  might 
have  been  done.  Several  observations  upon  the  activities  of  the 
females  in  the  summer  of  1908  had  led  the  observer  to  question  their 
ability  to  fly  ;  but  when  several  of  them  were  placed  upon  a  large 
sheet  of  paper  and  stirred  into  action,  they  disappeared  with  suffi- 
cient celerity  to  banish  any  doubts  which  may  have  been  entertained. 
In  considering  these  crude  experiments  in  retrospect  and  in  the  light 
of  subsequent  developments,  it  would  appear  that  their  jumping 
abilities  were  rather  underestimated,  because  it  is  now  certain  that 
they  are  either  unwilling  or  else,  like  the  female  of  their  host,  are 
unable  to  fly. 

A  most  careful  examination  of  egg  masses  in  the  vicinity  of  the 
locality  where  the  colony  of  about  500  had  been  liberated  the  summer 
before  had  failed  to  discover  the  presence  of  parasitized  eggs.  It  is 
now  known  that  this  was  due  to  the  accident  of  placing  this  colony 
in  a  locality  where  the  gipsy-moth  "wilt7'  disease  proved  later  to  be 
so  destructive  as  t<>  kill  all  the  pupae  which  were  present  when  the 
firsl  of  the  parasites  were  liberated,  and  which  it  was  then  thought 
would  produce  moths  enough  to  deposit  a  sufficiency  of  eggs  for 
attack.  As  a  result  of  tins  extreme  percentage  of  pupal  mortality, 
there  were  practically  no  eggs  within  a  radius  of  several  hundred 
feet. 

The  cause  of  failure  not  being  apparent,  it  was  guessed  that  it 
might  be  due  to  the  extremely  rapid  rate  of  dispersion  rather  than  to 
the  reverse',  and  to  provide  against  loss  through  too  rapid  dispersion 
at  first,  very  large  colonies  were  decide* I  upon  as  most  advisable. 


But.  91,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agriculture 


Plate  XI. 


Fig.  1.— Egg  of  Gipsy  Moth,  Containing  Developing 
Caterpillar  of  the  Gipsy  Moth.  Greatly  Enlarged. 
1  Original.' 


Fig.  2.— Egg  of  Gipsy  Moth,  Containing  Larva  of 
the  Parasite  Anastatus  bifasciatus.  Greatly 
Enlarged.  'Original.^ 


fa 

Fig.  3.— Egg  of  Gipsy  Moth,  Containing  Hibernating 
Larva  of  Anastatus  bifasciatus,  Which  in  Turn 
is  Parasitized  by  Three  Second-Stage  Larv/e  of 
schedius  kuvan/e.  greatly  enlarged.  'original.) 


Bui.  91,  Bureau  of  Entomology,  U.  S  Dept.  of  Agriculture, 


Plate 


XII. 


<  O 


z 

5  2 
°  55 

o 


uj  < 

<  C/5 

O  < 


EGG  PARASITES  OF  THE  GIPSY   MoT  11. 


173 


The  00,000  parasitized  eggs  were  divided  into  five  lots  and  placed  in 
the  field  at  the  proper  time  in  localities  where  an  abundance  of  eggs 
was  certain. 

The  parasites  hatched  in  due  course  and  were  found  attacking  the 
egg  masses  in  a  businesslike  manner  that  was  quite  encouraging, 
but  only  within  a  very  short  distance  of  the  center  of  the  colony. 
The  species  thus  spreads  slowly. 


Fig.  16.— Diagram  showing  two  years' dispersion  of  .4  no  statu  s  bifosn'otut  from  colony  center.  Each 
concentric  circle  represents  a  distance  of  .V)  feet  from  the  smaller  or  larger  circle  next  it.  .-I  indicates 
parasitism  of  gipsy-moth  egg-masses  l.y  Annxta'us  h>fn.-,  ,<itu<  and  O  indicates  al»ence  of  parasitism 
by  Anastatus.    The  figures  give  percentages  of  parasitism.    (  Original.) 

The  accompanying  diagram  (fig.  16),  which  has  been  prepared  by 
Mr.  Wooldrid^e  largely  from  the  results  of  his  own  work,  together 
with  Table  VIII,  will  serve  as  well  as  words  to  tell  the  story  of  the 
dispersion  of  this  parasite  in  one  of  the  1009  colonies,  and  results  of 
similar  studies  in  various  other  colonies  are  substantially  the  same. 


174  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Table  VIII. — Average  percentage  of  parasitism  of  gipsy-moth  egg  masses  at  different 

distances  from  center  of  colony. 


Distance  from  center. 

Number 
of  egg 
masses 

collected. 

Percent- 
age of  par- 
asitism. 

Distance  from  center. 

Number 
of  egg 
masses 

collected. 

Percent- 
age of  par- 
asitism. 

At  center  

20 
66 
78 
80 
60 
100 
85 

29.  26 
24.  68 
21.75 
14.  43 
8.  61 
3.  59 
3.  44 

350  feet  

50 
70 
60 
70 
70 
70 

0.  41 
.18 
.055 
.42 
.00 
.00 

50  feet  

400  feet  

100  feet  

450  feet..  

150  feet  

500  feet  

200  feet  

550  feet  

250  feet  

600  feet  

300  feet  

When  in  the  fall  of  1909  it  had  become  rather  certain  that  the  rate 
of  dispersion  of  Anastatus  was  only  going  to  be  about  200  feet  per 
year,  plans  for  colonization  along  very  different  lines  in  1910  were 
immediately  put  into  execution.  In  four  of  the  five  colonies  all  of 
the  egg  masses  which  could  be  easily  secured  were  collected  and 
brought  to  the  laboratory,  where  -the  eggs  were  separated  from  their 
hairy  covering.  This  is  best  effected  by  gently  rubbing  them  over 
a  piece  of  cheesecloth  stretched  on  a  frame.  (PL  XX,  fig.  2.) 
The  hairs  pass  through  and  the  eggs  are  left. 

The  number  of  parasitized  eggs  present  was  then  estimated,  and 
found  to  be  very  close  to  90,000.  In  the  spring,  after  all  of  the  healthy 
eggs  had  hatched,  those  remaining,  including  all  which  were  para- 
sitized, were  divided  into  100  lots,  each  of  which  was  supposed  to  con- 
tain approximately  900  parasite  larvse.  An  equal  number  of  small, 
wire-screen  cages  was  prepared  (PI.  XII,  fig.  1),  and  about  the  middle 
of  June,  when  the  male  parasites  began  to  issue,  and  when  it  was 
becoming  possible  to  determine  with  some  degree  of  assurance  just 
where  there  were  likely  to  be  large  numbers  of  gipsy-moth  eggs  a 
little  later,  the  work  of  placing  these  cages  in  the  open  was  begun. 
(See  also  PI.  XII,  fig.  2,  showing  front  and  bottom  of  cage  prepared  for 
use  in  Anastatus  colonization  in  191 1 .)  They  were  finally  placed,  each 
in  a  separate  locality,  and  each,  so  far  as  has  been  determined  by  sub- 
sequent investigation,  in  localities  where  the  parasites  had  an  excel- 
lent opportunity  to  work  to  the  best  advantage  as  soon  as  they  issued. 
Not  all  of  these  colonies  have  since  been  visited,  and  probably  some  of 
them  never  will  be  seen  again,  but  all  that  have  been  examined  have 
been  found  in  the  best  of  condition. 

Early  in  the  fall  of  1 910  the  dispersion  studies  of  1909  were  repeated , 
with  results  which  have  already  been  indicated  in  Mr.  Wooldridge's 
diagram,  and  the  egg  collections  were  also  repeated  for  the  purpose 
of  securing  material  for  additional  colonization  work  in  1911.  With 
lit  tie  difficulty  some  270,000  parasitized  eggs  have  been  secured,  and 
were  it,  not  for  the  fact  thai  the  proper  care  in  placing  the  number  of 
colonic-  thus  provided  for  will  probably  tax  all  available  resources 


EGG  PARASITES  OF  THE  GIPSY  MOTH. 


175 


at  the  time  when  they  must  be  placed,  if  placed  to  advantage,  more 
could  easily  he  collected. 

The  rate  of  increase  in  the  held,  as  indicated  by  the  work  which  lias 
been  done,  is  not  excessive,  but  probably  amounts  to  something  like 
sixfold  per  year.  The  extreme  limit  of  dispersion  discernible  in  1909 
was  not  quite  half  that  of  the  extreme  for  two  years,  as  indicated  in 
the  diagram.  It  is  possible  that  it  may  become  more  rapid  as  time 
goes  on,  and  it  is  rather  expected  that  a  high  wind,  at  an  opportune 
time,  will  assist  materially  in  the  dispersion  of  the  species.  Should  it 
not,  it  will  require  a  very  long  time  for  it  to  become  generally  estab- 
lished everywhere  through  the  infested  area.  Even  though  there 
were  a  colony  planted  to  each  square  mile,  something  like  16  years 
would  elapse  before  all  of  them  met  and  fused,  unless  the  present  rate 
of  dispersion  were  accelerated. 

It  has  been  pretty  definitely  proved  of  Schedins  that  it  can  only 
attack  the  uppermost  layer  of  eggs  in  each  mass,  and  the  same  is 
equally  well  proved  in  the  case  of  Anastatus.  Since  there  are  two 
layer>  of  eggs,  and  usually  three  in  all  but  the  very  smallest  masses,  it 
is  evident  thai  the  usefulness  of  Anastatus  is  still  further  reduced 
through  its  physical  limitations.  The  figures  of  percentages  given  in 
the  diagrams  probably  represent  about  the  maximum  which  can  ever 
be  expected.  None  the  less,  this  means  a  distinct  benefit,  and  with 
all  its  faults,  Anastatus  stands  high  in  favor  at  the  present  time. 

In  its  distribution  abroad.  Anastatus  is,  as  might  be  expected,  of 
quite  local  occurrence.  It  has  been  received  from  about  half  of  the 
localities  represented  by  the  European  importations,  and  in  very 
variable  abundance.  The  numbers  found  in  live  lots  of  what  was 
estimated  as  1 ,000  egg  masses  each,  received  from  live  different  locali- 
ties in  Hungary  through  Prof.  Jablonowski  in  the  winter  of  1908  9, 
is  rather  typical  in  this  respect.  As  estimated  through  careful  exam- 
ination and  counts,  these  numbers  were  as  follows: 


Laboratory 
Nu  in  ber." 

Locality. 

Number  of 

Anastatus. 

3017 

Lippa  (Temes)  

34,000 
0 
20S 
ti.OW 
3!UNN) 

79,307 

3018 

3019  

liustyhaza  (Maramoros)  

!  Iii^/.i  (  Maramoros)  

3020 

DorgOt  ( Tomes)  

3021, 

Sistarol>ecz  (Temes)  

Total  

In  Japan  it  is  also  unevenly  distributed.  The  most  which  were 
received  from  that  country  were  in  a  lot  of  eggs  from  Kukuoka  Ken, 
received  during  the  same  winter  as  those  above  mentioned  from  Hun- 
gary. It  is  not  at  all  common  from  the  vicinity  of  Tokyo,  and  while 
it  is  present  in  nearly  every  lot  of  Japanese  eggs  which  has  been  received, 
in  every  instance  but  one  (the  shipment  above  mentioned)  the  number 


176  PARASITES  OF  GIPSY  AND  BROWN -TAIL  MOTHS. 

present  has  not  been  sufficiently  large  to  make  the  rearing  of  the 
parasite  economically  worth  while.  It  is  interesting  and  possibly 
significant  that  there  was  no  Schedius  in  the  one  locality  where  Anas- 
tatus  was  sufficiently  common  to  be  considered  as  a  parasite  of  con- 
sequence, while  in  the  other  localities,  where  Anastatus  was  rare, 
Schedius  abounded.  More  than  one  instance  has  been  observed  in 
which  parasites  having  similar  habits  alternate  but  rarely  or  never 
occur  simultaneously  in  anything  like  equal  abundance  in  one  locality. 
Two  fairly  consistent  examples  of  this  sort  will  receive  further  men- 
tion later  on,  in  which  the  tachinids  Dexodes  nigripes  and  Compsilura 
concinnata,  and  Tachina  larvarum  and  Tricholyga  grandis  are  respec- 
tively involved. 

Schedius  kuvan.e  How. 

Only  one  species  of  gipsy-moth  egg  parasite  has  been  received  at 
the  laboratory  from  Europe,  but  in  Japan  there  are  two,  and,  so  far 


Fig.  17.— Schedius  kuvanx:  Adult  female.    Greatly  enlarged.    (From  Howard.) 


as  may  be  determined  from  their  comparative  abundance  in  the 
material  from  that  country  which  has  been  studied,  Schedius  Jcuvanae 
(fig.  1 7)  is  the  more  common  and  important  as  a  factor  in  the  control 
of  its  host.  It  resembles  Anastatus  in  its  choice  of  host,  and  in  the 
fact  that  it  is  similarly  limited  through  physical  inability  from  attack- 
ing more  than  a  limited  percentage  oft  he  eggs  in  each  mass.  In  every 
other  respect  the  two  species  are  widely  different. 

Anastatus  is  a  true  egg  parasite,  and  rarely  attacks  successfully 
tlie  eggs  in  which  the  young  caterpillars  have  begun  to  form.  She- 
dius,  on  the  contrary,  is  strictly  speaking  an  internal  parasite  of  the 
unhatehed  caterpillar.    Anastatus  pas.-es  through  but  one  genera- 


EGG  PARASITES  OF  THE  GIPSY  MOTH. 


177 


tion  annually,  and  its  seasonal  history  is  closely  correlated  with  that 
of  its  host.  Schedius,  on  the  contrary,  will  pass  through  a  generation 
per  month,  so  long  as  the  temperature  is  sufficiently  high,  and  its 
seasonal  history  is  in  no  way  correlated  to  that  of  the  gipsy  moth. 
It  appears  not  to  hibernate  in  the  gipsy-moth  eggs,  and  it  is  quite 
probable  that  an  alternate  host  is  necessary  to  cany  it  through  the 
summer  months  after  the  gipsy-moth  eggs  have  hatched  in  the  spring, 
and  before  the  moths  begin  depositing  eggs  for  a  new  generation. 

At  the  time  when  the  popular  account  of  the  parasite-introduction 
work  was  prepared  for  publication  through  the  office  of  tho  Massa- 
chusetts State  Forester  it  was  considered  to  be  much  the  more 
promising  of  the  egg  parasites,  and  its  history  in  America  was  spoken 
of  as  one  "of  the  most  satisfactory  episodes  in  the  work  of  parasite 
introduction."  The  account  of  the  first  successful  importation  of 
living  specimens  as  given  at  that  time  is  included  in  the  two  follow- 
ing paragraphs,  which  arc  quoted  verbatim. 

As  long  ago  us  the  spring  of  a  few  dead  adults  were  secured  in  an  importation 
of  gipsy-nioih  egg  masses  received  during  the  winter  frmn  Japan,  but  none  was  living 
on  receipt.  During  the  winter  next  following,  large  importations  were  made,  and 
many  thousands  of  eggs,  from  which  some  parasite  had  emerged,  were  found,  but  not 
a  single  living  specimen  was  obtained.  It  was  evident  that  it  completed  its  trans- 
formations ami  issued  in  the  fall,  and  that,  if  it  hibernated  in  the  eggs,  it  was  warmed 
to  activity  while  the  packages  were  in  transit  to  America,  and  the  adult  parasites 
either  died  pf  escaped  en  route. 

In  tie-  fall,  winter,  and  spring  of  1  !M)S-<>  a  large  quantity  of  eggs  of  the  gipsy  moth 
were  received  from  Japan,  the  shipments  beginning  early  in  the  fall  and  continuing 
until  nearly  time  for  tho  caterpillars  to  hatch  in  the  spring.  The  first,  received  in  Sep- 
tember, contained  hundred-,  possibly  thousands,  of  the  parasites,  which  had  issued 
from  the  eggs  en  route,  and  all  of  which.  a<  UMial,  had  died;  not  a  single  living  individ- 
ual was  received.  Specimen-  were  referred  to  I>r.  Howard,  who  found  that  they 
represented  an  entirely  new  and  hitherto  undeseribed  species,  which  he  named  after 
Prof.  Kuwaua.  who  collected  and  sent  the  eggs  from  which  they  had  issued.  A  single 
pair  of  living  specimens  rewarded  the  careful  attention  which  was  lavished  upon  the 
importations  received  later  in  the  fall  and  during  the  winter,  and  it  was  not  until 
April,  !!)()!>,  that  a  mated  pair  could  be  secured.  During  that  month  a  total  of  11 
individuals  issued  from  cages  containing  Japanese  eggs  recently  received. 

These  11  individuals  served  as  the  progenitors  of  a  numerous  and 
prolific  race,  but  the  story  of  the  investigations  which  were  made 
upon  the  various  shipments  of  egg  masses  received  at  the  laboratory 
from  September,  190S,  to  April,  1909,  which  was  not  touched  upon 
in  an  earlier  account,  is  perhaps  worthy  of  a  place  here. 

LIFE   OF  SCHEDIUS  AND  ITS   RELATIONS  TO   OTHER   EGO  PARASITES,   PRIMARY  AND 

SECONDARY. 

Mention  has  already  been  made  of  the  rearing  of  a  small  encyrtid 
parasite  from  Japanese  eggs  in  company  with  Anastatus  in  the  sum- 
mer of  1908,  of  the  doubts  which  were  felt  as  to  its  true  character, 

Do(37T° — Bull.  91—11  ll> 


178 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


and  of  the'  resolve  to  investigate  the  matter  thoroughly  when  the 
opportunity  should  arise.  In  accordance  with  this  resolve  an  inten- 
sive study  of  the  Japanese  importations  was  begun  in  December, 
1908.  A  large  number  of  egg  masses,  which  showed  by  the  exit 
holes  (of  Schedius)  that  they  had  been  freely  attacked  by  some  para- 
site which  had  issued  in  the  fall,  were  selected,  then  "sifted,"  and 
the  eggs  from  each  mass  Avere  then  carefully  examined  and  sorted 
into  three  lots,  composed,  respectively,  of  the  healthy  eggs,  the  eggs 
from  winch  parasites  had  issued,  and  the  eggs  which  were  neither 
one  nor  the  other.  Those  falling  in  this  third  division  were  scrutin- 
ized again  with  still  more  care.  Anastatus  was  quickly  recognized, 
in  most  instances,  and  eggs  containing  its  larvae  placed  aside.  In 
the  majority  of  the  remainder  there  was  evidently  no  life,  but  in 
a  considerable  number  minute,  white  larvae  could  more  or  less 
plainly  be  seen,  surrounded  and  more  than  half  concealed  by  the 
remains  of  the  embryonic  caterpillars  which  had  been  destroyed. 
These  eggs  were  isolated  in  small  vials,  in  order  that  there  could  be 
no  question  concerning  the  identity  of  the  particular  host  egg  from 
which  any  particular  parasite  issued. 

Long  before  this  work  was  completed  the  necessity  for  all  the  care 
that  was  being  expended  to  secure  accurate  results  was  made  mani- 
fest by  the  emergence  of  no  less  than  three  species  of  parasites  from 
isolated  or  partially  isolated  eggs.  The  first  of  these  to  appear  was  a 
species  of  Pachyneuron(  determined  by  the  senior  author  as  P.  gifuen- 
sisAshm.),  and  on  account  of  known  habits  of  other  members  of  the 
genus  was  placed  as  probably  secondary.  Nevertheless  it  was  given 
an  opportunity  to  prove  itself  a  primary  if  it  would,  and  the  speci- 
mens as  they  issued  were  confined  in  vials  with  gipsy-moth  eggs, 
some  of  which  contained  the  healthy  caterpillars,  while  others  har- 
bored the  larvae  of  Anastatus.  The  Pachyneuron  paid  not  the  slightest 
attention  to  either,  but  invariably  died  without  attempting  ovipo- 
sition. 

The  next  species  to  issue  was  Tyndarichus  navx  How.,  and  it  was 
with  considerable  surprise  that  it  was  recognized  as  different  from 
Schedius.  On  account  of  the  strong  superficial  resemblance  between 
the  two  it  had  been  supposed  up  to  that  time  that  they  were  one 
and  the  same. 

The  third  was  Perissopterus  javensis  How.,  of  which  a  single  speci- 
men only  was  reared.  To  date  this  record  is  unique,  and  the  species 
has  previously  been  reared  only  from  scale  insects. 

There  was  other  and  pressing  work  to  be  done  with  the  parasites 
of  the  hibernating  brown-tail  caterpillars,  and  a  realization  of  the 
difficulties  which  were  likely  to  attend  the  prosecution  of  the  egg- 
parasite  investigations,  thus  complicated  by  the  discovery  that  five 
and  possibly  more  parasites  were  involved  of  which  only  one  was 


EGG  PARASITES  OF  THE  GIPSY  MOTH. 


179 


definitely  proved  to  be  primary,  was  the  prime  argument  which  finally 
resulted  in  the  detachment  of  Mr.  II.  S.  Smith  from  the  cotton  boll 
weevil  investigations  and  his  transfer  to  the  laboratory  staff.  By 
the  time  he  was  prepared  to  undertake  his  new  work  a  large  number 
of  eggs  from  which  Anastatus,  Tyndarichus,  and  Paehyneuron  were 
positively  known  to  have  issued  were  ready  for  dissection  and  study, 
and  to  these  were  soon  added  a  number  from  which  Schedius  was 
similarly  known  to  have  come,  secured  in  the  manner  about  to  be 
described. 

The  first  Schedius  which  was  ever  reared  in  a  living  condition 
issued  from  an  isolated  egg  in  the  laboratory  in  December,  1908.  It 
was  a  male,  and  it  died  before  it  could  be  furnished  with  a  mate. 
The  next  individual  issued  on  January  S  from  an  egg  which  had  been 
isolated  on  December  19,  It  was  a  female,  and  she  was  immediately 
transferred  to  a  large*  vial  containing  an  egg  mass  Freshly  collected 
from  the  field.  Within  a  few  days  after  being  thus  confined  she  was 
observed  in  the  act  of  oviposit  ion.  and  part  henogenetic  reproduction 
ensued.  I  Ier  progeny  began  to  issue 
February  10,  and  up  to  February  2."> 
no  less  than  28  males  were  reared. 

The  experiment  was  tried  <>1"  con- 
fining her  witli  several  of  her  asexu- 
ally-produced  progeny  in  the  hope 
that  she  might  thus  be  fertilized  and 
produce  Females.  The  experiment  Fio.  lA.SehedUukm9nm:  Egg.  Greatly  en- 
,.  ,      .  i    ,  ,1    .  (Original.) 

did  not  succeed  at  t  hat  t  line,  appar- 
ently because  she  was  not  able  to  deposit   any  more  eggs.  She 
remained  alive  until  March  2,  hut  was  dead  on  March  G,  after  at 
least  eight  weeks  of  active  life. 

The  eggs  from  which  these  part  henogenet  ically-produced  males  issued 
were  known  beyond  peradvent ure  of  a  doubt  to  have  produced  Sche- 
dius, and  never  to  have  contained  any  other  parasite,  and  together 
with  those  from  which  Anastatus,  Tyndarichus,  and  Paehyneuron 
were  known  to  have  issued,  made  complete  the  3eries  which  was  to 
be  dissected. 

The  dissection  work  was  mostly  done  by  Mr.  Smith,  but  he  was 
not  alone  when  it  came  to  puzzling  over  the  problems  in  parasite 
anatomy  and  parasitic  interrelations  which  this  work  produced  in 
abundance.  The  contents  of  the  individual  eggshells  were  scruti- 
nized with  the  utmost  care,  and  slowly  the  various  anatomical 
remains  found  therein  were  associated  with  one  parasite  or  another. 

In  the  course  of  these  studies  it  was  discovered  that  Schedius 
deposits  a  large  egg  (fig.  18),  which  is  supplied  with  a  very  long 
stalk.  The  egg  is  placed  within  the  body  of  the  unhatched  but 
fully  formed  caterpillar,  with  the  end  of  the  stalk  projecting  outside. 


180 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Sometimes,  and  apparently  usually,  the  end  of  this  stalk  passed 
through  the  shell  of  the  egg  as  well  as  through  the  body  of  the  cater- 
pillar, as  indicated  in  the  figures  (fig.  19,  PI.  XI,  fig.  3).  When  the  egg 
hatches,  the  larva  does  not  entirely  leave  the  shell,  but  remains  with 

its  anal  end  thrust  into  it,  and  the  stalk, 
which  is  hollow,  becomes  functional  and  acts 
like  a  lifeline  attached  to  a  submarine  diver 
in  supplying  a  connection  with  the  outer  air. 
As  the  larva  grows  the  stalk  increases  in  thick- 
ness, and  the  last  anal  segment  of  the  larva 
becomes  covered  with  a  thick  chitinized  shield, 
which  is  unaffected  by  the  action  of  strong 
caustic  potash.  There  are  two  larval  molts, 
and  consequently  three  larval  stages.  During 
the  entire  course  of  both  the  first  and  second 
the  young  parasite  remains  quite  firmly  at- 
tached to  its  anal  shield  and  lifeline  and  the 
cast  skins  are  not  entirely  sloughed  off,  but 
are  merely  pushed  backward.  After  the  third 
ecdysis  it  retains  this  connection  for  awhile, 
and  grows  rapidly,  but  about  the  time  when 
it  reaches  maturity  the  connection  with  the 
shield  is  broken,  thus  proving  that  it  is  not  part  and  parcel  of  the 
integument.  It  would  appear  rather  that  this  shield,  including  a  tube 
within  the  egg-stalk  (which,  as  stated,  grows  in  thickness  after  the 
egg  itself  hatches),  is  actually  part  of  the  integument 
of  the  first-stage  larva,  and  that  the  second  and  third 
stages  merely  continue  to  use  what  is  in  effect  the  skin 
of  the  first  larval  molt. 

The  host  caterpillar  is  completely  destroyed  except 
for  the  harder  chitinous  parts,  head,  tarsal  claws,  hooks 
of  the  prolegs,  etc.,  and  the  hair,  which  is  left  in  a  sort 
of  hank,  more  or  less  completely  surrounding  and  con- 
cealing the  parasite  larva.  It  is  impossible  to  distin- 
guish between  the  larvae  of  Schedius  and  those  of  its 
secondaries  from  an  external  examination  of  the  eggs. 

After  the  larva  reaches  its  full  growth  and  casts  off 
its  anal  shield,  it  quickly  pupates  (fig.  20)  and  very 
shortly  thereafter  issues  as  an  adult.     There  is  no  indication  of  a 
desire  to  hibernate  during  any  part  of  the  preliminary  stages,  in 
which  respect  Schedius  differs  from  nearly  every  other  chalcidid  which 
has  been  studied  at  the  laboratory. 


Fig.  19—  Schedius  Tcuvanx: 
Third-stage  larva  still  retaining 
attachment  to  egg-stalk,  and 
anal  shield.  Greatly  enlarged. 
(Original.) 


Fig.  20. — Scfu  diue 
kuvahx:  Pupa. 
Greatly  en- 
larged. (Origi- 
nal.) 


EGG  PARASITES  OF  TTIE  GTPSY  MOTH. 


181 


Schedius  is  to  all  purposes,  if  not  to  all  intents,  a  secondary  para- 
site upon  occasion.  In  the  spring  of  1909  a  generation  was  carried 
through  to  maturity  within  the  larvae 
of  Anastatus,  and  at  that  time  there 
w  as  no  difficulty  experienced  in  induc- 
ing the  Schedius  females  to  oviposit  in 
such.  In  the  course  of  later  experi- 
ments which  were  designed  to  deter- 
mine whether  there  was  any  preference 
shown  between  the  eggs  containing 
healthy  caterpillars  and  those  with  the 
larva*  of  Anastatus,  only  the  healthy 
eggs  were  selected  for  oviposit  ion  by 
the  parent  females.  What  was  more, 
although  several  later  attempts  were 
made  to  force  Schedius  to  oviposit  in 
eggs  containing  Anastatus  larva1,  none 
but  the  first  w  as  successful. 

Oftentimes  two  or  more  eggs  are 
deposited  in  one  host.  Numerous  in- 
stances have  been  found  in  which  second-stage 


Fig.  21.— Schtdius  luvanx:  Egg-stalk  ami 
anal  shield  of  larva  as  found  in  host 
eggs  of  gipsy  moth  from  which  the  adult 
Schedius  has  emerged,  or  in  which  the 
Schedius  larva  has  been  attacked  by  a 
secondary  parasite.  Greatly  enlarged. 
(Original.) 


larvae  were  feeding 


peaceably 
still  more 


Bide 
have 


Fig.  Zl.—ScfHrfiii*  l:\nanst: 
Larval  mandibles.  Greatly 
enlarged.  Original.) 


by  side  as  the  result  of  such  superparasitism,  and 
been  observed  in  which  the  former  presence  of  more 
than  one  individual  was  positively  indicated 
by  t  lie  presence  of  more  than  one  egg-stalk 
and  anal  shield,  but  never,  out  of  many 
thousands  of  examples  under  observation, 
has  more  than  one  adult  parasite  issued 
from  one  egg.  What  happens  to  the  su- 
pernumerary individuals  is  not  indicated 
further  than  that  they  disappear,  and  that 
their  substance  goes  to  nourish  the  sole  survivor.  Whether  there 
is  an  actual  struggle  for  supremacy  in  which  victory  comes  to 
the  strongest,  or  whether  the  struggle 
takes  the  form  of  a  contest  to  deter- 
mine which  shall  quickest  consume 
the  available  food  supply,  the  loser 
calmly  surrendering  his  body  to  the 
winner  by  way  of  forfeit,  has  never 
beei)  revealed. 

The  story  of  a  triple  tragedy  is  told  in  Plate  XI,  figure  3,  w  hich  is 
drawn  from  a  slide  prepared  by  Mr.  Smith.  It  represents  a  single 
gipsy-moth  egg,  which  had  been  attacked  by  Anastatus  before  the 
embryonic  caterpillar  had  developed  sufficiently  to  leave  percept  ible 


Fig.  28. — TyniarichlU  noise:  Larval  man- 
dibles.   Greatly  enlarged.  (Original.) 


182 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Fig.  24. — Pachyneuron  gifu- 
ensis:  Egg.  Greatly  en- 
larged. (Original.) 


remains.  The  Anastatus,  after  consuming  the  entire  contents  of  the 
eggshell  had  reached  the  hibernating  stage,  and  settled  down  to 

some  10  months  of  inactivity,  when  it  was 
attacked  by  Schedius.  No  less  than  three 
Schedius  eggs  were  deposited  in  fairly  rapid 
succession  (but  probably  by  different  parents) 
since  the  three  larvae,  the  outlines  of  which 
are  shown,  are  practically  equal  in  size.  All 
are  apparently  about  ready  to  molt  for  the  second  time,  and  after 
this  molt,  if  they  had  been  allowed  to  live,  one  would  most  certainly 
have  gained  the  mastery  and  devoured  the  others. 

But  this  conflict  for  supremacy,  sanguinary  as  it  is,  is  only  the 
beginning  of  what  might  occur  in  the  open  in  Japan.  Tyndarichus 
and  Pachyneuron  are  both  habitually  and  essen- 
tially secondary  parasites,  and  both  prey  not  only 
upon  Schedius,  but  upon  each  other  with  perfect 
impartiality.     Either  might  attack'  the  surviving 
Schedius,  and  be  in  turn  the  victim  of  the  other,  Fig.  25.— Pachyneuron 
and  there  is  no  apparent  reason  why  Schedius    Q'fuensis:  larval 

1  1  J  mandibles.  Greatly 

should  not  return  to  the  fray  and,  by  destroying    enlarged.  (Origi- 
its  own  secondary,  start  the  battle  all  over  again.       nal  ) 

Such  a  long-drawn-out  contest  is  hardly  likely  to  occur  very 
often,  but  in  many  instances  tales  scarcely  less  sanguinary  have  been 
told  by  the  relics  which  strewed  the  field  of  battle.  Among  these 
relics  the  anal  shield  with  egg  stalk  and  the  characteristic  mandibles 
(figs.  21  and  22,  respectively)  have  served  as 
positive  indication  of  the  former  presence  of 
Schedius.  Tyndarichus  is  betrayed  by  its 
mandibles  (fig.  23),  which,  like  those  of  Sched- 
ius, retain  their  characteristic  form  through 
all  three  stages.  The  former  presence  of 
Pachyneuron,  curiously  enough,  is  quite  easily 
recognizable  by  its  characteristic  eggshell  (fig. 
24),  which  is  of  a  substance  which  defies  the  action  of  hot  concen- 
trated caustic  potash  siiflicently  prolonged  to  result  in  the  complete 
solution  of  the  gipsy-moth  eggshell.  It  may  also  be  recognized  by 
its  mandibles  (fig.  25),  which  are  rather  small  and  inconspicuous  in 
any  but  the  last  stage.  Anastatus,  when  its  former  presence  can 
be  proved  at  all,  may  be  recognized  by  its  mandibles  also  (fig.  26), 
but  these  are  so  small  as  to  be  very  difficult  to  find,  and  it  is  alto- 
gether probable  that  there  have  been  eggs  dissected  in  which  Anas- 
f  at  us  was  the  original  primary  parasite,  but  of  which  fact  no  proof 
remained. 


Fig.  26.— Anastatus  bifas- 
ciatus:  Larval  mandi- 
bles. Greatly  en- 
larged. (Original.) 


F.C(i   PA HAS  IT  KS  OF  T1IK  (JIPSY  MOTH. 


183 


Tn  order  thai  some  idea  may  be  had  of  the  conditions  which  actually 
prevail  in  the  open  in  Japan,  results  of  the  dissection  of  43  eggs 
from  Japanese  importations  arc  given  below.  Many  other  eggs  were 
dissected,  in  some  of  which  the  tale  was  too  complicated  to  be  un- 
raveled, and  it  is,  of  course,  necessary  to  leave  out  of  consideration 
here  the  results  of  those  dissections  which  were  made  before  the 
significance  of  that  which  was  found  was  fully  recognized. 

In  the  formula?  which  follow  the  symbols  are  to  be  read  as  follows: 

X  =  Parasitized  by;  +  =  Superparasitized  by. 

Thus  the  conditions  represented  in  the  figure  to  which  attention 
has  already  been  drawn  would  be  expressed: 

PorUhir  'xi  <iispar  X  Anastatus  X  Schedius. 

4-  Schedius. 
-f  Schedius. 

The  host  rdat  ions  revealed  by  dissect  i<>n-  of  eggs  from  which  Pachy- 
QeuroD  emerged  are  similarly  indicated  as  follows: 

Dispar  X  Schedius  X  Pachyneuron  (20  times). 
Dispar  X  Schedius  X  Pachyneuron. 

4-  Pachyneuron  (1  time). 

Dispar  X  Schedius. 

4-  Schedius  X  Pachyneuron  (3  times). 
Dispar  X  Schedius. 

4-  Schedius. 

4-  Schedius. 

4-  Schedius. 

4-  Schedius  X  Pachyneuron  (1  time). 
Dispar  X  Anastatus  X  Pachyneuron  (1  time). 
Dispar  X  Anastatus. 

4  Schedius  X  Pachyneuron  I  time). 

Dissections  of  eggs  from  which  Tyndarichus  emerged  resulted  as 
follows  : 

Dispar  X  Schedius  X  Tyndarichus  (11  times). 
Dispar  X  Schedius. 

4-  Schedius  X  Tyndarichus  (2  times). 
Dispar  X  Schedius. 

4-  Schedius  X  Tyndarichus. 

4-  Tyndarichus  (1  time). 
Dispar  X  Schedius  X  Pachyneuron. 

4-  Tyndarichus  (1  time). 
Dispar  X  Anastatus  <  Tyndarichua  1 1  time). 

Mention  has  already  been  made  of  the  parthenogenesis  of  Schedius, 
and  the  fact  that  only  males  were  produced  in  the  first  attempt  of 
successful  reproduction  experiments  in  which  only  a  single  female 
was  available.  Numerous  subsequent  experiments  have  demon- 
strated beyond  question  that  thelyotoky  is  the  rule  and  that  excep- 
tions are  rare  if  they  ever  occur. 


184 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


In  the  course  of  the  first  unavoidable  experiment  in  partheno- 
genesis the  attempt  was  made  to  secure  the  fertilization  of  the  female 
through  union  with  her  own  asexually  produced  offspring,  but, 
although  she  lived  after  they  had  completed  their  transformations,  no 
results  were  secured.  It  seemed  to  be  within  the  bounds  of  possi- 
bility that  success  would  follow  if  the  experiment  were  differently 
conducted,  and  accordingly  in  the  fall  of  1909  Mr.  Smith  repeated 
it,  with  this  variation,  that  the  females,  after  they  had  deposited  a 
few  eggs,  were  rendered  dormant  by  exposure  to  moderate  cold, 
awaiting  the  issuance  of  their  progeny.  This  time  no  difficulty  was 
experienced.  The  parthenogenetically  produced  males  mated  freely 
with  their  respective  parents,  and  the  subsequent  progeny  in  each 
of  several  instances  consisted  of  both  sexes. 

Females  thus  reared  were  mated  with  their  brothers  (which  were 
at  the  same  time  their  nephews),  reproduced  with  the  ordinary 
freedom,  and* their  progeny  were  of  both  sexes  in  the  usual  proportions. 
Still  another  generation  showed  no  signs  of  weakness  or  any  sort  of 
abnormality,  and  the  experiment  was  discontinued. 

In  sexual  reproduction  the  males  appear  always  to  be  largely  out- 
numbered by  the  females.  Nothing  like  the  diversity  in  this  respect 
which  has  been  noted  in  the  case  of  other  chalcidids  has  been  observed 
in  the  case  of  Schedius. 

REARING  AND  COLONIZATION. 

When  the  first  individuals  of  Schedius  were  secured  from  the 
imported  Japanese  egg  masses  in  April,  1909,  there  was  no  difficulty 
in  securing  reproduction  upon  gipsy-moth  eggs  collected  in  the  open, 
but  by  the  time  the  second  generation  was  secured  those  which  had 
remained  in  the  open  were  about  to  hatch,  and  would  hatch  almost 
immediately  they  were  brought  indoors.  A  large  quantity  of  eggs 
had  been  placed  in  cold  storage  in  anticipation  of  this,  and  it  was 
found  that  these  would  hatch  nearly  as  quickly  when  they  were 
removed.  Oviposition  at  any  time  within  a  few  hours  of  the  time 
when  the  eggs  would  otherwise  hatch  was  generally  successful,  but 
when  the  eggs  hatched  within  36  hours  after  being  exposed  to  the 
degree  of  warmth  necessary  to  secure  oviposition  of  the  parasite,  it 
soon  became  evident  that  not  very  much  increase  was  to  be  expected. 
Accordingly,  tin1  experiment  was  made  of  killing  tfce  host  eggs  through 
exposure  to  just  enough  heat  to  bring  this  about.  The  parasites  ovi- 
posited in  these  dead  eggs  with  the  same  freedom  that  they  would 
attack  the  living,  and  reproduction  ensued.  The  progeny,  however, 
were  small  and  weak,  and  not  as  prolific  as  those  secured  earlier  in 
the  spring. 

Thus,  in  one  way  and  another  the  species  was  carried  through  the 
summer,  and  with  the  deposition  of  fresh  gipsy-moth  eggs  early  in 
July  much  better  results  were  secured,  and  the  parasites  immediately 


roc;  Parasites  of  tiik  tnpsv  moth. 


185 


began  to  increase  rapidly  in  numbers  with  each  succeeding  generation. 
By  AiiLTu-t  there  were  enough  to  make  a  small  colony  in  the  open 
possible  without  depleting  the  laboratory  stock  to  a  serious  extent, 
and  firsi  one  and  later  several  small  colonies  were  established  in 
various  localities  in  the  moth-infested  area. 

At  the  same  time  reproduction  work  was  continued  on  an  ever- 
increasing  scale  at  the  laboratory,  and  by  the  iirst  of  the  next  year 
no  less  than  1,000,000  individuals,  at  a  conservative  estimate,  were 
present  in  our  rearing  cages.  Further  attempts  to  increase  this 
number  were  not  successful,  on  account  of  the  difficulties  attending 
the  handling  of  such  an  immense  number  at  a  time  when  the  hatching 
of  the  host  eggs  followed  too  soon  after  their  removal  to  high  tem- 
perature. 

The  numbers  in  the  laboratory  Buffered  no  decrease,  however,  and 
by  the  end  of  March  colonization  work  on  an  extensive  scale  was 
begun.  The  parasitized  eggs  were  divided  into  100  lots,  each  of 
which  contained  approximately  10,000  of  the  parasite,  and  these 
were  distributed  to  agents  of  the  State  forester's  oflice,  who  placed 
them  in  the  held  in  the  hope  and  expectation  that  the  parasites 
issuing  from  them  would  reproduce  immediately  upon  the  gipsy-moth 
eggs  before  the  latter  hatched. 

There  was  also  a  large  quantity  of  parasitized  eggs  remaining,  and 
these  were  placed  in  cold  storage  in  the  hope  that  the  emergence  of 

the  brood  might  be  retarded  until  the  fresh  eggs  of  the  gipsy  moth 
should  be  available  for  attack  in  the  latter  part  of  the  summer.  This 
hope  was  not  justified,  because  when  the  time  came  and  the  eggs 
were  taken  from  cold  storage  not  a  single  living  parasite  remained. 

In  Table  IX  are  summarized  the  results  of  the  reproduction  work, 
as  conducted  in  the  Laboratory  from  April,  1909,  to  the  winter  of 
1909-10,  and  the  dates  when  the  first  colonies  were  planted  in  the 
late  summer  and  fall  are  therein  indicated. 


Table  IX.  —  Jictnlts  of  n ■•production  irnrk  uitlt  Scfudius. 


Gcner- 
ation. 

N u in  1  >er  and  source  of  pan  •  n  1 1 . 

Reproduction  work 
begun. 

Emergence  of  prog- 
eny. 

Total 
nuinlter  of 
progeny. 

Colo- 
nized. 

Began. 

Ended. 

First 

11  from  imported  egg  masses. . 

lit  from  first  generation  

645  from  second  generation  

1.350 from  third  generation  

1.01'.*  from  fourth  generation... 
3,00ti  from  fif  t  h  generat  ion    . . 
7,355  from  sixth  generation.. . 
20,784  from  seventh  gener- 
ation. 

199.512  from  eighth  gener- 
ation. 

204,  too  from  ninth  generation. 

Apr.  19  

Mav  19 
June  23 
July  10 
Aug.  It'. 
Sept.  11 
Oct.  5 
Oct.  29 

June  14 
July  If. 
Aug.  10 
Sept.  7 
Sept.  29 
Oct.  25 
Nov.  15 

114 
iw."> 
1,350 
11.999 

•;. 

12.723 
35.423 
l  219,  (.27 

1  1,028,301 

I  9,<U  779 

S.vond.. 

Third.... 
Fourth... 
Fifth.... 

Sixth  

Seventh.. 
Eighth... 

Ninth.... 

Tenth.. 

May  19  

Julv  It.  

Aug.  16  

Sept.  11  

10.  9M) 
3.2*0 
5.3U.S 
5,639 

20,115 

733, 967 
•'mi.  7A9 

Sept.  30  

Oct.  25  

Nov.  21-Dec.21 

Tan. 

1  Estimated. 


186 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


The  reproduction  of  the  parasite  in  the  field  as  a  result  of  these 
early  attempts  at  colonization  was  far  in  excess  of  expectations. 
The  rate  of  reproduction  in  the  laboratory  (as  indicated  in  the  table) 
was  greatly  exceeded  in  the  open,  and  hundreds  of  thousands  of  eggs 
in  the  immediate  vicinity  of  the  colony  sites  were  known  to  be 
parasitized  when  the  coming  of  cold  weather  put  a  stop  to  insect 
activity.  In  the  one  colony  which  was  most  closely  watched,  the 
parasitized  eggs  averaged  some  30  to  the  mass  (fig.  27),  while  every- 
where within  50  yards  of  the  center  egg  masses  were  so  thick  in  spots 

as  to  hide  the  bark  on  the  trees. 
Beyond  the  distance  mentioned  the 
number  per  mass  fell  off  very  rapidly, 
but  some  were  found  several  hundred 
yards  away  from  the  point  of  libera- 
tion, in  striking  contrast  to  the  re- 
sults following  the  colonization  of 
Anastatus. 

In  October  adults  of  what  ap- 
peared to  be  the  second  generation 
were  not  uncommon  in  the  field,  and 
on  any  warm  day  they  could  be 
found,  apparently  ovipositing  for  a 
third  generation.  At  the  same  time 
larvae  and  pupae  were  in  abundance, 
and  only  a  few  days'  exposure  to  the 
warmth  of  the  laboratory  was  needed 
to  bring  them  out  from  eggs  collected 
in  the  field.  Collections  of  eggs  were 
made  from  time  to  time  during  the 
fall,  in  order  that  assurance  might 
thus  be  had  of  the  continued  well- 
being  of  the  parasite,  and  until  De- 
cember nothing  untoward  occurred. 
The  first  real  winter  weather  came 
^    „_  ^  ,  .  ,      at  the  end  of  that  month,  and  a  few 

Fig.  27 —Gipsy-moth  egg  mass,  showing  exit  holes 
of  Schedius  kuvanse.    Enlarged  about  four  times,  days    later    a    lot    OI  eggS  Was  COl- 

(0riginal }  lected  and  brought  in.    Not  a  sin- 

gle parasite  issued.  The  experiment  was  repeated  and  with  the 
same  results,  and  although  many  hundreds  of  masses  have  since  been 
collected  (some  of  them  in  the  spring,  after  the  caterpillars  had 
issued  for  the  purpose  of  determining  whether  there  might  not  be 
reproduction  of  hibernated  adults  at  that  time,  and  the  rest  of  them 
in  the  fall  to  see  if  by  any  chance  the  parasite  had  escaped  detection 
in  the  spring),  no  trace  of  its  existence  could  be  found.    In  every 


EGG  PARASITES  OF  THE  GIPSY  MOTH. 


1ST 


instance,  so  far  as  the  above-mentioned  colony  was  concerned,  the 
results  were  the  same,  and  there  seems  to  be  no  doubt  that,  in  this 
oarticular  locality  at  least,  the  species  has  become  extinct. 

In  the  spring  one  large  colony  of  the  Schedius  was  planted  coinci- 
dently  with  the  distribution  of  the  100  lots  of  parasitized  eggs  for 
colonization  by  the  State  forester's  agents,  and  for  two  months  fol- 
lowing weekly  collections  of  eggs  were  made  with  the  expectation  that 
a  partial  spring  generation  would  follow.  None  of  these  collected 
egg  masses  produced  the  parasite,  and  again  it  failed  to  come  up  to 
that  which  was  expected  of  it. 

In  the  fall,  as  has  already  been  mentioned,  very  large  collections  of 
eggs  made  in  the  vicinity  of  that  which  was  considered  to  be  the  best 
and  most  promising  of  the  colonies  of  1  909  failed  to  produce  Schedius, 
and  at  the  same  time  numerous  smaller  collect  ions  were  made  in  each 
of  the  other  colonies  of  1909,  as  well  as  in  a  considerable  number  of  the 
spring  colonies  of  1910.  In  only  one  of  the  colonies  of  190!)  was  the 
Schedius  recovered,  and  this,  curiously  enough,  from  that  in  which 
every  at  tempt  had  been  made  to  secmc,  evidence  of  spring  repro- 
duction. Here  it  was  found  in  one  direction  from  the  center  of  the 
colony  only,  and  over  a  rather  limited  area.  In  the  immediate  vicin- 
ity of  the  colony  site  (within  KM)  yards)  none  could  be  found. 

The  collections  which  were  made  in  each  of  the  other  colonies  of 
1909  were  followed  by  curiously  similar  resi  Its.  The  parasite  was 
recovered  in  one  of  them,  and  in  one  Only,  and  although  collections  of 
eggs  were  made  in  all  directions  from  the  center  and  at  varying 
distances,  parasit  i/.ed  egg  0188808  were  only  found  in  a  limited  area 
to  one  side  and  some  distance  aw  ay. 

It  was  pretty  conclusively  demonstrated  that  the  larva1  and 
pupa1  of  Schedius  could  not  survive  the  rigor  of  the  winter,  and  it  is 
very  difficult  to  say  whether  the  recovery  of  the  parasite  in  this 
last-mentioned  instance  is  indicative  of  its  ability  to  survive  the 
winter  as  an  adult.  In  1909  a  quantity  of  the  adults  was  placed  in 
a  small  cage  in  the  open  before  the  beginning  of  severe  weather, and, 
although  mortality  was  heavy,  some  of  them  lived  for  a  long  time 
after  all  of  the  younger  stages  were  destroyed.  None  of  them  lived 
through  until  spring,  but  there  is  nothing  to  prove  that  they  would 
not  have  done  so  had  they  had  their  choice  of  situations  in  which  to 
hibernate. 

It  may  be  that  females  successfully  hibernated  in  the  instance  of 
this  colony,  which  appeal's  to  have  lived  throughout  one  year  in  the 
open.  It  may  also  be  that  the  recovery  of  the  species  under  these 
conditions  is  the  result  of  dispersion  of  the  individuals  from  some  of 
the  many  spring  colonies,  several  of  which  were  located  within  a  not 
unreasonable  distance  of  this  spot.  It  will  require  another  year  to 
demonstrate  the  truth  of  the  matter. 


188 


PARASITES  OP  GTPSY  AND  BROWN-TAIL  MOTHS. 


The  recovery  of  Scliedius  under  any  conditions  at  all  was  con- 
sidered as  sufficient  to  justify  the  repetition  of  the  rearing  work  of  the 
winter  before,  and  accordingly,  using  a  few  individuals  secured  from 
the  field  early  in  the  fall,  a  series  of  generations  has  been  reared  in  the 
laboratory  until  the  number  now  on  hand  (Jan.  1,  1911)  runs  into  the 
hundreds  of  thousands.  In  the  spring  it  is  planned  to  establish  one 
or  two  exceedingly  large  new  colonies,  sufficiently  far  distant  from 
any  of  the  others  to  make  the  recovery  of  the  parasite  elsewhere  a 
certain  indication  that  it  is  able  to  pass  the  winter  in  New  England 
and  thereby  justify  the  labors  which  have  been  expended  in  its 
behalf. 

THE  PARASITES  OF  THE  GIPSY-MOTH  CATERPILLARS. 

APPARENTLY  UNIMPORTANT  HYMENOPTEROUS  PARASITES. 

It  would  be  presumption  to  state  without  qualification  that  the 
parasites  which  are  here  brought  together  as  unimportant  are  in 
reality  that.  It  may  well  be  that  among  them  are  some  which  will 
be  of  sufficient  promise  to  make  advisable  the  trouble  and  expense 
incident  to  an  attempt  to  transplant  them  to  America,  and  which  will 
serve  to  fill  in  the  gap  in  the  sequence  which  the  apparent  failure  of 
Apanteles  fulvipes  has  left.  To  determine  more  definitely  their 
relative  importance  abroad  is  one  of  the  objects  of  the  work  for  the 
season  of  1911,  as  at  present  planned,  and  something  more  than  is 
known  now  is  certain  to  be  known  a  year  from  now  unless  the  plans 
for  the  season  go  wrong  from  the  beginning. 

The  various  species  coming  in  this  category  are  called  unimportant 
because  they  have  never  been  received  in  imported  material  in 
numbers  sufficient  to  make  colonization  in  America  possible,  and  only 
upon  very  rare  occasions  and  in  the  instance  of  a  few  amongst  them 
only,  in  numbers  sufficient  to  indicate  that  they  were  of  any  impor- 
tance whatever  in  effecting  the  control  of  their  host  abroad. 

The  investigations  into  the  parasites  and  parasitism  of  various 
native  insects  more  or  less  similar  in  one  respect  or  another  to  the 
gipsy  moth  have  served  to  throw  considerable  light  upon  the  status 
of  such  parasites  as  these.  It  has  been  shown,  in  the  instance  of 
the  tussock  moth,  that  a  parasite  may  be  entirely  absent  in  localities 
where  the  host  is  abundant,  or  else  very  rare  under  such  circumstances 
and  yet  be  sufficiently  common  to  effect  an  appreciable  amount  of 
control  in  localities  where  the  host  is  very  rare.  It  is  thus  possible 
thai  some  among  these  species  may  play  a  very  important  role  in 
keeping  its  host,  when  already  reduced  to  relatively  small  numbers, 
from  increasing  sufficiently  to  become  of  economic  importance,  and 
fchal  .'it  the  same  time  they  may  play  no  part  at  all  in  reducing  that 
insect  from  a  state  of  or  approaching  noxious  abundance  to  within 
its  ordinary  limits. 


PARASITE^  OE  ( ;  I  PS  Y-M  OTI I   C ' AT ERFUXABS. 


189 


On  the  other  hand,  studies  with  the  parasites  of  native  insects 
have  revealed  the  existence  of  what  may  be  called  accidental  or 
incidental  parasites.  These  may  he  important  parasites  of  one 
insect  and  of  no  importance  whatever  in  connection  with  another, 
nearly  allied.  Sometimes  this  is  due  to  the  fact  that  the  one  species 
of  host  may  excite  in  the  mother  parasite  the  desire  to  oviposit,  which 
is  not  excited  by  the  other,  and  occasionally,  as  has  more  than  once 
been  observed,  the  pres- 
ence of  the  favored  host 
in  the  immediate  vicinity 
will  induce  the  parasite 
to  oviposit  in  another 
species  which    and  e  r 

otherwise  identical  cir- 
cuinst  anccs  would  be  en- 
tirely ignored.  At  other 
times  an   insect  may 

be  acceptable  to  t  h  e 

mother  parasite,  but  for 
s<»mc    reason  unaccept- 
able to  her  progeny ,  80  that  only  a  very  few  out  of  the  many  eggs 
which  are  deposited  will  go  through  to  maturity,  and  the  species  will 
be  of  necessity  considered  as  rare  and  unimportant. 

The  fact  that  there  are  included  in  every  list  of  the  parasites  of  a 
given  host  a  few  species  which  are  thus  to  be  considered  as  incidental 
or  accidental  lends  force  to  the  contention  that  among  the  recorded 
parasites  of  the  gipsy  moth  are  several  at  least  which  come  into  the 


Yv;.  js.-.l 


ilitarius:  Adult  female  and  cocoon.  En- 
larged. (Original.) 


same  category, 
time. 


Just  which  these  aie  is  not  altogether  plain  at  this 


Apantelks  si  •  i  rr.vKius  Katz. 


Cocoons  of  a  solitary  species  of  Apanteles  (fig.  L>s0  which  attacks 
the  very  young  to  half-grown  caterpillars  of  the  gipsy  moth  through- 
out the  greater  part  if  not  the  whole  of  Kurope  have  occasionally  been 
received  in  shipments  in  which  the  caterpillars  were  not  all  in  the  last 
or  next  to  the  last  stage.  In  those  shipments  which  consisted  of  cater- 
pillars in  the  third,  fourth,  and  fifth  stages  at  the  time  of  collection, 
the  cocoons  of  this  species  have  been  the  most  common.  In  no 
instance  has  a  sufficient  number  been  received  to  lfiake  possible  any- 
thing like  a  satisfactory  colony  of  this  species,  and  in  all  scarcely  more 
than  100  have  been  received  since  the  beginning  of  the  work. 

The  parasite  undoubtedly  attacks  the  first-stage  caterpillars  as 
well  as  those  of  the  later  stages  up  to  the  fourth  at  least,  and  per- 
haps the  fifth.  The  host  probably  molts  at  least  once,  subsequent 
to  attack,  and  remains  alive  after  the  emergence  of  the  parasite  larva, 


190 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


clinging  to  and  seeming  to  brood  over  the  cocoon  of  its  mortal  enemy. 
Numerous  experiments  have  been  made  with  other,  similarly  living 
caterpillers  from  which  parasites  have  emerged,  in  an  attempt  to  make 
them  feed,  and  invariably  these  attempts  have  been  unsuccessful. 

Of  all  of  the  gipsy-moth  parasites  in  Europe  of  which  there  is  no 
present  prospect  of  introduction  into  America,  this  species  is  the 
most  promising,  and  yet,  if  dependence  is  placed  upon  the  results  of 
the  rearing  records,  it  is  so  scarce  as  to  be  wholly  inconsequential  as 
a  parasite  of  this  host. 

Meteorus  versicolor  Wesm. 

Very  occasionally  cocoons  of  this  common  brown-tail  moth  parasite 
have  been  found  in  boxes  of  gipsy-moth  caterpillars  received  from 
European  sources,  but  never  in  any  numbers.  Altogether  not  nearly 
so  many  have  been  received  as  of  the  cocoons  of  Apanteles  solitarius. 

It  is  apparently  an  incidental  parasite  of  no  consequence,  and  were 
it  not  an  enemy  of  the  brown-tail  moth  as  well,  it  is  very  improbable 
that  any  attempt  would  be  made  to  introduce  it  into  America. 

As  a  parasite  of  the  brown-tail  moth  it  is  of  considerable  promise, 
and  as  a  brown-tail  moth  parasite  it  has  been  introduced  and  is 
apparently  at  this  time  thoroughly  established  over  a  considerable 
territory.  Upon  several  occasions  it  has  been  reared  from  gipsy  moth 
caterpillars  collected  in  the  field  localities  where  it  was  particularly 
common  as  a  parasite  of  the  brown-tail  moth,  but,  as  in  Europe,  it 
expresses  a  strong  preference  for  the  last-mentioned  host. 

Meteorus  pulchricornis  Wesm. 

Quite  a  number  of  this  species  has  been  reared  from  cocoons  found 
in  the  boxes  of  gipsy -moth  caterpillars  received  from  southern  France, 
and  a  very  few  have  also  been  received  from  Italy.  None  of  the 
Meteorus  which  have  been  reared  from  the  brown-tail  moth  in  any 
part  of  Europe  have  been  anything  else  than  M.  versicolor,  so  far  as 
known.  It  is,  of  course,  possible  that  two  species  similar  in  appear- 
ance might  easily  have  been  confused,  and  no  attempt  has  been  made 
to  determine  the  specific  identity  of  every  specimen  which  has  been 
reared  for  liberation. 

There  is  nothing  to  indicate  that  M.  pulchricomis  is  ever  of  more 
consequence  as  a,  parasite  of  the  gipsy  moth  than  is  M.  versicolor, 
and  until  evidence  to  the  contrary  is  forthcoming  it  will  not  be  con- 
sidered as  of  importance  or  promise. 

Meteorus  iafonicus  Ashm. 

Specimens  of  this  species  were  secured  from  boxes  of  young  gipsy- 
mot  h  caterpillars  from  Japan  in  very  small  numbers  in  1908  and  1909, 
but  so  far  as  could  be  determined  it  was  of  no  more  importance  in 


PAliASITES  OF  CilPSY-MOTII   CAT KHPI  l.LAKS. 


191 


that  country  than  were  either  of  the  two  species  already  mentioned  in 
Europe.  In  the  winter  of  1909-10  a  few  specimens  were  received 
from  Mr.  Kuwana,  together  with  the  statement  that  it  was  common 
as  a  parasite  of  the  gipsy  moth  in  Xagaoka,  hut  not  in  Tokyo  in  1908. 
Attempts  to  import  it  in  1910  were  unsuccessful,  and  it  is  with  the 
hope  of  confirming  its  importance,  at  least  locally,  and  discovering 
some  method  of  transplanting  it  to  America,  should  such  confirmation 
come  about,  that  the  investigations  are 
undertaken  in  Japan  in  the  year  1911. 

LOfNSBIUM  DISPARLS  VlER. 

This  interesting  parasite  was  first  re- 
ceived in  June.  P. 107.  in  a  shipment  of 
small  gipsy-moth  caterpilla  re  from  Kief, 

Russia.      A  total  of    IS  of  its  peculiar     VlG-  ^■-^mneriwm  disparis:  Cocoon. 

•      i  •     t  Rotated.  (OrigtnaL) 

cocoons  (fig.  29)  was  received  m  June 

and  July  of  that  year  in  boxes  which  contained  only  a  relatively 
small  number  of  caterpillars  when  sent,  and  its  importance  as  a 

parasite  appeared  to  be  considerable.  It  seemed  probable  that  the 
larva1  spinning  them  had  issued  from  caterpillars  in  the  fourth  and 
fifth  stages. 

The  cocoons  usually  approach  more  nearly  the  spherical  than  that 
used  as  the  type  for  the  drawing.     The  walls  are  thin,  but  SO  dense 

as  not  only  to  be  impervious 
to  moisture,  but  to  prevent 
the  drying  of  the  ineconial  dis- 
charge for  months. 

None  of  the  cocoons  was 
hatched  on  receipt.  A  single 
male  adult  (fig.  30  »  issued  from 
one  of  these  cocoons  in  August . 
No  more  adults  appearing, 
some  of  the  cocoons  were 
opened  from  time  to  time  dur- 
ing the  fall  and  found  to  con- 
tain still  living  adults.  Since 
it  is  known  that  several  of  the 

FlG.  30.— Limnrrium  disparts:  Adult  male.    Much  on-      nativo  species  which  SPUt  silll- 

Larged.  (Original.)  1        '  }   .  .. 

liar  cocoons  actually  do  hiber- 
nate as  adults  within  the  cocoon,  it  is  reasonable  to  suppose  that  the 
same  is  true  of  this. 

No  adults  were  reared,  however,  and  their  failure  to  emerge  appears 
to  be  due  to  the  drying  during  the  winter  of  the  semiliquid  meconial 
discharge  which  effectually  glued  the  adults  to  the  sides  of  the  cocoon 
and  prevented  their  further  movement. 


192  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

The  several  native  species  spinning  similar  cocoons  attack  a  variety 
of  hosts,  and  one  of  them,  L.  clisiocampse,  is  sometimes  common  and 
quite  effective  as  a  parasite  of  the  host  indicated  by  its  specific  name. 
The  larvae,  after  spinning  the  cocoon  and  before  discharging  their 
meconium,  are  very  active  for  a  period  of  about  24  hours,  convul- 
sively wriggling  the  body  in  such  a  manner  as  to  make  the  spherical 
cocoon  move  about  in  an  extraordinary  manner.  It  is  altogether 
probable  that  the  gipsy-moth  parasite  has  the  same  characteristic, 
and  that  the  cocoons  so  spun  in  the  trees  are  quickly  dislodged,  fall 
to  the  ground,  and  become  hidden  beneath  leaves  and  debris. 

Prof.  Kincaid  was  especially  instructed  to  seek  for  evidences  of 
parasitism  by  this  species  in  Russia  on  the  occasion  of  his  trip  to 
that  country  in  1909.  He  did  not  find  it  at  all  abundant,  however, 
and  only  secured  three  or  four  cocoons.  In  1910  the  junior  author 
sought  diligently  for  these  cocoons  in  the  forest  about  Kharkof, 
where  the  caterpillars  had  been  very  abundant  the  season  before, 
but  he  was  entirely  unsuccessful  and  as  a  result  thoroughly  convinced 
that  it  was  not  an  important  parasite  in  any  of  the  several  forests 
visited.  There  was  no  opportunity  at  Kief  to  make  a  similar  search, 
because  the  caterpillars  had  not  been  sufficiently  abundant  within 
recent  years  in  any  of  the  localities  visited  to  make  likely  the  discovery 
of  these  cocoons,  even  though  the  species  had  been  of  importance  as 
an  enemy  of  the  gipsy  moth. 

In  1909  and  again  in  1910  it,  or  another  practically  indistinguish- 
able species,  was  received  in  very  small  numbers  from  Japan,  but  at 
the  same  time  under  circumstances  which  were  in  a  way  as  suggestive 
of  the  possible  importance  of  the  species  as  were  those  under  winch 
it  was  first  received  from  Russia,  as  detailed  above.  As  in  the  case 
of  the  Japanese  Meteorus,  it  is  hoped  to  be  able  to  determine  defi- 
initely  whether  it  is  to  be  considered  as  of  more  than  technical  interest 
in  the  connection  in  which  it  is  here  considered. 

LlMNERIUM  (AxiLASTUS)  TRICOLORIPES  VlER. 

From  time  to  time  several  specimens  of  Limnerium  cocoons,  all  of 
them  oblong  in  shape,  and  most  of  them  partially  concealed  by  the 
skin  of  the  host  caterpillar,  have  been  received  from  Europe.  In  no 
instance  have  they  been  in  sufficiently  large  numbers  to  make  the 
species  appear  promising  as  a  parasite. 

Less  than  a  dozen  specimens  have  been  received,  all  told,  and  were 
it  not  for  the  fad  that  the  remains  of  the  host  accompanied  the 
cocoon,  il  would  not  be  possible  thus  definitely  to  associate  the  para- 
site with  its  host. 


PARASITES  OF  GIPSY-MOTH  CATERPILLARS. 


193 


Apanteles  fulvipes  Hal. 

The  one  among  the  hymenopterous  parasites  attacking  the  cater- 
pillars of  the  gipsy  moth  which  has  ever  been  received  under  circum- 
stances indicative  <of  its  unquestioned  importance  as  an  enemy  of 
that  host  is  at  present  known  as  Apanteles  fulvipes  (fig.  31).  The 
name  Glyptapanteles,  as  generic-ally  applied  to  it.  has  been  regret- 
fully dropped,  the  more  so  since  this  name  has  already  become  familiar 
to  many  whose  interest  in  parasites  begins  and  ends  with  those  which 
are  included  among  the  enemies  of  the  gipsy  and  brown-tail  moths. 
It  was  accepted,  in  the  first  place,  on  account  of  the  immediate  dis- 
tinction which  it  offered  to  Apanteles,  as  applied  to  A.  solitarius  and 
A,  lacteicolor  Vier., 
and  because  it 
seemed  preferable  to 
make  the  technical 
name  the  common 
name  as  well.  Now, 
with  an  enforced 
change  in  the  spe- 
cific name  vaguely 
in  prospect,  it  would 
seem  advisable  to 
adopt  an  arbitrary 
C  o  m  m  o  D  n  a  in  e 
rather  than  to  at- 
tempt to  popularize 
the  technical  name, 
and  should  it  again 
become  desirable  to 
write  of  it  in  a  pop- 
ular way,  this  will 

,    '  Pte.  31.—A  jiantdt.* /vMpM.*  Adult.  Greatly  enlarged.  (From  Howard.) 

probably  be  done. 

That  a  change  in  its  specilie  designation  will  become  necessary  when 
it  shall  have  been  thoroughly  well  studied  abroad  seems  probable, 
although  there  is  no  basis  upon  which  to  make  such  a  change  at  the 
present  time.  If,  as  European  taxonomists  have  agreed,  it  is  synony- 
mous with  A.  nemonutt,  described  by  Ralzeburg  as  a  parasite  of 
Lasiocaiu pa  pint  L.  and  is  at  the  same  time  specifically  identical  wit  h 
the  form  so  determined  by  Marshall  as  a  common  species  in  England, 
there  seems  to  be  no  reason  why  it  should  not  be  introduced  success- 
fully into  Massachusetts.  A  parasite  with  anything  like  the  wide 
range  of  hosts  accredited  to  this  species  abroad  should  find  no  difli- 
culty  in  existing  in  America,  and  if  the  species  which  attacks  the 
U50770— Bull.  91— U  13 


194 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


gipsy  moth  is  proved  to  be  identical  with  that  which  goes  under  the 
same  name  and  attacks  one  or  another  of  such  a  variety  of  hosts,  no 
expense  ought  to  be  spared  in  attempting  its  introduction;  always 
provided,  of  course,  that  the  attempts  already  made  prove  not  to  be 
successful. 

The  story  of  these  attempts,  as  told  in  the  popular  bulletin  by  the 
junior  author,  issued  from  the  Massachusetts  State  forester's  office 
in  the  spring  of  1910,  may  well  be  quoted  here,  since  there  is  little 
to  be  added  to  it. 

Although  this  was  almost  the  first  parasite  of  the  gipsy  moth  which  attracted  any 
attention  in  Massachusetts,  and  the  first  which  it  was  attempted  to  import  after  the 

beginning  of  active  work,  it  was  one  of  the  last  to 
be  liberated  under  satisfactory  conditions,  and 
its  establishment  in  America  is  not  yet  certain. 
Extraordinary  methods  were  necessary  to  bring 
it  to  America  living  and  healthy,  and  it  was  not 
until  Prof.  Trevor  Kincaid,  who  was  selected  by 
Dr.  Howard  as  the  best  available  man  for  the 
purpose,  visited  Japan  and  personally  superin- 
tended the  collection  and  shipment  of  the  co- 
coons, that  success  was  achieved.  The  story  of 
Prof.  Kincaid's  experiences  and  of  the  difficulties 
which  he  met  and  overcame  is  interesting.  He 
was  accorded  great  and  material  assistance  by 
the  Japanese  entomologists,  and  the  work  inaugu- 
rated by  him  in  1908  was  continued  with  even 
greater  success  in  1909. 

The  adult  parasite  [fig.  31]  deposits  a  number 
of  eggs  beneath  the  skin  of  the  active  caterpillars, 
and  any  stage,  from  the  first  to  and  possibly  in- 
cluding the  last,  may  be  attacked.  The  larvae, 
hatching  from  the  eggs,  become  full  grown  in 
from  two  to  three  weeks,  and  then  work  their 
way  out  through  the  skin  of  the  still  living  cat- 
erpillar [fig.  32],  within  the  body  of  which  they 
fed.  Each  spins  for  itself  immediately  afterward, 
for  its  better  protection  during  its  later  stage?, 
a  small  white  cocoon.  The  number  of  parasites  nourished  by  a  single  host  varies  in 
accordance  with  its  size.  There  may  be  as  few  as  2  or  3  in  very  small  caterpillars, 
or  100  or  more  in  those  which  are  nearly  full  grown. 

The  unfortunate  victim  of  attack  does  not,  as  a  rule,  die  immediately  after  the 
emergence  of  the  parasite  larvae  and  the  spinning  of  their  cocoons,  but  it  never  volun- 
tarily moves  from  the  spot.  Its  appearance,  both  before  and  after  death,  surrounded 
by  and  seeming  to  brood  over  the  cocoons,  is  peculiar  and  characteristic,  and  once 
seen  can  never  be  mistaken  [fig.  33]. 

There  is  ample  opportunity  for  two  generations  of  the  parasite  annually  upon  the 
caterpillars  of  one  generation  of  the  gipsy  moth.  This  is  the  rule  in  the  countries  to 
which  it  is  native,  and  is  to  be  expected  in  America. 

The  parasite  was  described  from  Europe  more  than  seventy-five  years  ago,  and  has 
been  known  to  be  a  parasite  of  the  gipsy  moth  lor  a  long  time.  Later  it  was  described 
under  a  different  name  from  Japan,  and  the  Japanese  parasite  was  for  a  time  consid- 


Fig.  32.— Apanteles  fuh  ipes:  Larva)  eav 
ing  gipsy-moth  caterpillar.  Enlarged 
(Original.) 


PARASITES  OF  GIPSY-MOTH  CATERPILLARS. 


195 


ered  to  be  different  from  the  European.  Absolutely  no  differences  in  life  and  habit 
which  mn  serve  to  separate  the  two  are  known,  and.  as  the  adults  are  also  indistin- 
guishable in  appearance,  they  are  considered  to  be  identical. 

It  has  been  the  subject  of  frequent  mention  under  the  name  of  Apanteles,  as  well  as 
of  Glyptapanteles,  in  the  various  reports  of  the  (superintendent  of  moth  work,  from 
the  first  to  the  fourth;  and  Dr.  Howard,  in  the  account  of  his  first  trip  to  Europe  in  the 
interests  of  parasite  introduction,  tells  of  its  occurrence  in  the  suburbs  of  Vienna. 
Largely  on  aeoountof  the  fact  that  it  is  much  more  conspicuous  than  many  of  the  other 
parasites,  it  has  attracted  more  genera!  attention.  The  Rev.  H.  A.  Loomis.  a  mis- 
sionary, and  resident  of  Yokohama,  was  the  first  to  call  attention  to  its  importance  in 
Japan,  and  made  several  unsuccessful  attempts  t<»  send  it  to  America.  Dr.  G.  P. 
Clinton,  mycologist  of  the  Connecticut  Agricultural  Experiment  Station,  who  visited 
Japan  in  1909,  observed  the  parasite  at 
work,  and  reported  most  favorably  upon 
its  efficiency  as  a  check  to  the  moth.  Nu- 
merous other  attempts  on  the  pari  of  Euro- 
pean and  Japanese  entomologists,  including 
one  elaborate  experiment  which  involved 
the  shipment  of  a  large  wire-screened  eau'o 
containing  a  living  tree  with  pipsy  caterpil- 
lars and  the  parasite,  wen-  made,  but  with 
uniformly  ill  success.  1'pon  every  occasion 
the  parasites  all  emerged  from  their  eoeo<ms 
and  died  en  route. 

When  every  other  means  failed.  Prof. 
Kineaid.  as  already  stated,  was  deputed  to 
visit  Japan,  and  to  make  all  necessary  ar- 
rangements for  the  transportation  of  the 
parasite  cocoons  in  cold  storage  to  America. 
The  ftrnUDgementfl  which  he  perfected  pro- 
vided tor  continuous  cold  storage,  not  only 
en  route  across  the  Pacific,  but  during 
practically  every  moment  from  the  time 
the  cocoons  were  collected  in  the  field  in 
Japan   until    they    were   received  at  the 

laboratory  in  Melrose.  Events  justified  the 
adoption  of  every  precaution,  and,  with  all 
the  care,  only  a  small  part  of  the  very  largo 
quantity  of  cocoons  which  he  collected 
reached  their  destination  in  good  condition. 
Hundreds  of  thousands  were  collected  and 
shipped,  and  less  than  50,000  were  received 
alive — nearly  all  in  one  shipment  in  July. 

The  season  in  Massachusetts  was  early, 
and  nearly  all  of  the  gipsy  caterpillars  had 
pupated  by  that  time,  so  that  there  was  no  opportunity  for  the  parasite  t<>  increase  in 
the  field  upon  this  host  that  season.  In  1909  the  sites  of  the  colonies  we  re  frequently 
visited,  but  not  a  single  parasitized  caterpillar  was  found  which  could  he  traced  to 
colonizations  of  the  year  before.  Keen  disappointment  was  at  first  felt,  but  later 
developments  have  tended  to  throw  a  more  encouraging  light  upon  the  situation. 

In  1909  importations  were  continued,  through  the  magnificent  efforts  of  Prof.  S.  I. 
Kuwana,  of  the  Imperial  Agricultural  Experiment  Station  at  Tokio,  with  much  more 
satisfactory  results.    In  1908  the  season  in  Japan  was  very  late,  and  it  was  not  practi- 


Fig.  M.—Apantchsfuli  ipts:  Cocoons  surround- 
ing dead  gipsy-moth  caterpillar.  Slightly  en- 
larged. (Original.) 


196  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


cable  to  send  any  of  the  cocoons  of  the  parasite  until  June  and  July;  while  in  America 
the  season  was  early,  and  by  that  time  all  of  the  caterpillars,  as  has  already  been  stated, 
had  pupated.  In  1909  the  season  was  rather  early  in  Japan  and  correspondingly  late 
in  America;  and,  besides,  through  special  effort,  Prof.  Kuwana  was  enabled  to  send  a 
few  thousands  of  the  cocoons  of  the  first  generation,  which  reached  the  laboratory 
early  in  June.  About  1,000  adults  emerged  from  these  cocoons  after  receipt,  and  the 
most  of  them  were  placed  in  one  colony  in  a  cold  situation  on  the  North  Shore,  where 
the  caterpillars  were  greatly  retarded,  and  where  there  were  still  some  in  the  first 
stage.  The  remainder  were  colonized  in  warmer  localities,  where  the  caterpillars 
were  one  stage  farther  advanced. 

Immediate  success  followed  the  planting  of  these  colonies.  Within  three  weeks 
cocoons  were  found  in  each,  and  the  number  of  parasitized  caterpillars  was  gratify- 
ingly  large.  A  very  careful  investigation  was  conducted,  to  determine  the  proportion 
which  was  attacked  by  native  secondary  parasites;  and,  while  this  was  so  large  in  one 
instance  as  seriously  to  jeopardize  the  success  of  the  experiment,  it  was  not  so  large  in 
the  others. 

There  were  several  thousands  of  this  first  generation  known  to  have  developed  in 
the  open  upon  American  soil,  which  issued  from  the  cocoons  some  four  or  five  weeks 
after  the  colonies  were  established,  but  in  only  that  one  on  the  North  Shore,  where  the 
caterpillars  were  in  the  first  and  second  stages  when  the  parasites  were  liberated,  was 
there  a  full  second  generation.  Here  the  larger  caterpillars  were  again  attacked,  and 
an  abundant  second  generation  of  the  parasite  followed. 

Meanwhile,  additional  shipments  of  cocoons  of  the  second  Japanese  generation  were 
received  early  enough  to  permit  of  a  generation  in  the  open  upon  the  native  cater- 
pillars, and  several  other  colonies  were  successfully  established.  It  is  known  that 
there  were  many  thousands  of  the  parasite  issuing  in  at  least  five  different  localities 
during  August,  but  immediately  thereafter  they  were  completely  lost  to  sight,  and 
it  is  futile  to  hope  to  recover  traces  of  them  before  another  spring. 

Until  the  late  summer  of  1909  nothing  occurred  to  indicate  that  this  parasite  would 
be  likely  to  fly  for  any  great  distance  from  the  point  of  its  liberation;  and,  as  has  been 
already  stated,  it  was  looked  for  in  vain  in  the  summer  of  1909  in  the  immediate  vicin- 
ity of  the  colonies  of  the  year  before.  In  July,  1909,  a  strong  colony  was  planted  in  an 
isolated  woodland  colony  of  gipsy  moths  in  the  town  of  Milton.  It  was  rather  confi- 
dently expected  that  it  would  attack  these  caterpillars  so  extensively  as  to  destroy 
the  major  portion;  but  it  was  the  cause  of  some  surprise,  when  the  locality  was  visited 
after  the  parasites  of  the  new  generation  had  mostly  issued  from  the  affected  cater- 
pillars, to  find  a  smaller  number  of  cocoons  than  there  were  individuals  liberated  in 
the  first  place,  and  only  about  one-fourth,  perhaps  less,  of  the  caterpillars  attacked. 
The  circumstance  was  as  discouraging  as  anything  which  had  gone  before,  and'for  a 
few  days  nothing  happened  to  change  its  complexion.  Then,  to  the  intense  surprise 
of  the  writer,  Mr.  Charles  W.  Minott,  field  agent  of  the  central  division,  sent  to  the 
laboratory  a  bona  fide  example  of  the  parasite,  which  had  been  collected  in  the  Blue 
Hills  reservation,  upwards  of  a  mile  away.  There  was  no  possible  source  except  the 
Milton  colony,  and  a  spread  of  upwards  of  a  mile  in  something  under  a  week  was  indi- 
cated beyond  dispute.  At  almost  the  same  time  the  brood  of  Monodontomerus  was 
found  for  the  first  time  in  pupae  of  the  gipsy  moth  in  the  field;  and  when  the  history  of 
this  species  is  considered,  in  the  connection  which  it  bears  toward  the  circumstances 
surrounding  the  recovery  of  the  Glyptapanteles  so  far  from  the  point  where  it  was 
liberated,  the  whole  situation  is  altered. 

Granted  that  the  parasite  disperses  at  the  rate  of  one  mile  in  each  week  of  activity, 
and  that  it  is  able  to  adapt  its  life  and  habits  to  the  climate  and  conditions  in  America, 
the  chances  are,  dial,  instead  of  looking  for  it  in  the  immediate  vicinity  of  the  points 
of  colonization,  it  is  quite  as  likely  to  be  found  almost  anywhere  in  (he  infested  area 


PARASITES  OF  (UPSY-MOT  1 1    (  ATI' IIP  I  I.LAliS. 


197 


witliin  2")  miles  of  Boston.  If  it  is  thus  generally  distributed,  very  large  numbers  in 
the  ajTLrrcu'atc  may  exist,  and  it  may  increase  at  a  rate  as  rapid  as  that  of  Monodonto- 
merus,  and  at  the  same  time  escape  detection  until  the  summer  of  1911  or  1912. 1 

There  is  not  very  much  to  add  to  the  account  given  above,  further 
than  the  statement  that  all  attempts  to  recover  the  species  in  the 
field  in  L910  from  the  vicinity  of  colonies  of  the  year  before  failed.  It 
hardly  seems  likely  that  so  conspicuous  an  object  as  the  cocoon 
mass  of  this  parasite  should  escape  the  notice  of  the  many  field 
men  who  are  familiar  with  its  appearance,  and  who  know  of  the 
great  interest  and  importance  which  would  attach  to  its  discovery. 
Inconsequence  the  failure  to  recover  the  species  is  of  more  signifi- 
cance than  the  failure  in  the  instance  <>!*  any  other  parasite  which 
could  be  menl  ioned. 

At  the  same  time  all  hope  has  Dot  been  given  up,  especially  in 
consideration  of  the  curious  circumstances  which  will  shortly  be 
described,  surrounding  the  recovery  of  I'U  nnmihis  ({jnyius  as  a  para- 
site of  the  brown-tail  moth.  If,  as  can  no  longer  be  doubted,  a  minute 
and  to  all  appearances  an  inactive  insect  like  Pteromalus  has  dis- 
persed over  a  territory  of  approximately  1  ().()()()  square  miles  within 
five  years  as  the  extreme  limit,  and  if  during  that  period  it  remained 
so  rare  as  to  defy  all  of  our  efforts  to  recover  it.  it  is  not  impossible 
that  AjKinifhs  fuJr'tjKS  will  do  the  same.  Should  this  come  about, 
the  year  L91 1  or  1912  would  probably  witness  its  sudden  and  simulta- 
neous appearance  throughout  the  greater  pari  of  the  territory  infested 
by  t  he  gipsy  mot  h. 

It  miht  be  confessed,  however,  that  hope  rather  than  faith  has 

dictated  these  la>t  lines.  It  is  believed,  and  not  without  some  foun- 
dation, t  hat  the  failure  of  - 1  panU  l<  sfuhipi  a  to  exist  here  is  due  to  t  he 

absence  of  an  absolutely  Qece8Sary  alternate  host ,  and  that  further 
attempts  to  introduce  it  will  be  unavailing.  Thai  is  the  reason  why 
the  most  will  be  made  of  every  opportunity  to  determine  the  truth 
or  fallacy  of  the  European  records  w  hich  accredit  it  with  attacking  a 
variety  of  insects  representing  half  a  dozen  families,  and  two  or  three 
times  that  number  of  genera,  many  of  which  are  represented  by 
closely  allied  and  sometimes  by  the  same  species  in  America.  If 
investigations  uphold  the  truth  of  these  records,-  no  expense  ought  to 
be  spared  in  further  attempts  to  establish  the  parasite  in  America, 
because  of  all  those  which  attack  the  gipsy  moth  it  is  the  one  which 
was  not  only  the  most  promising  at  the  beginning,  but  which  remains 
the  most  desired  at  the  present  time. 

1  The  occurrence  of  the  cocoons  in  the  near  vicinity  of  the  colony  sites  immediately  following  the  libera- 
tion is  most  natural,  and  in  perfect  harmony  with  the  wide  dispersion.  The  female  parasites  as  soon  as 
they  emerge  are  ready  to  deposit  a  small  part  of  the  eggs  which  they  will  eventually  deposit  if  they  live  and 
have  opportunity.  After  the  deposition  of  this  part,  it  is  necessary  for  them  to  wait  an  appreciable  tune 
before  they  are  ready  to  deposit  any  more. 


198  PARASITES  OF  GIPSY  AND  BR  OWN -TAIL  MOTHS. 

In  1910  additional  importations  were  made  from  Japan,  and  a  large 
number  of  healthy  adults  was  liberated  sufficiently  early  in  the  season 
to  allow  for  one  generation  upon  the  gipsy  moth.  As  in  1909,  cocoon 
masses  were  found  in  the  vicinity  of  these  colonies  about  three  weeks 
after  their  establishment. 

An  attempt  will  be  made  in  1911  to  import  enough  cocoons  from 
Russia  to  make  possible  a  strong  colony  of  the  European  race.  It  is 
possible  that  it  would  succeed  here  when  the  Japanese  would  fail, 
and  on  the  chance  the  experiment  is  undertaken. 

SECONDARY  PARASITES  ATTACKING  APANTELES  FULVIPES. 

It  is  safe  to  say  that  a  better  opportunity  for  an  intensive  study  of 
the  parasites  of  any  one  host  which  was  itself  a  parasite  has  never  been 
afforded  than  has  come  about  at  the  laboratory  in  the  case  of  the 
parasites  of  Apanteles  fulvipes. 

Hundreds  of  thousands  of  the  cocoons  of  the  primary  parasite  were 
collected  in  Japan  after  they  had  been  exposed  to  attack  by  the  sec- 
ondaries, and,  so  far  as  can  be  judged,  the  latter  stood  the  ordeal  of 
the  journey  to  America  better  than  did  the  primary.  Even  in  those 
shipments  which  were  just  a  few  days  too  long  en  route  and  in  which 
the  Apanteles  themselves  had  all  issued  and  died  before  their  receipt 
the  secondaries  had  hardly  begun  to  issue.  These,  as  well  as  the 
numerous  shipments  which  were  received  in  better  condition,  in  so  far 
as  Apanteles  was  concerned,  have  produced  many  thousands  of  sec- 
ondary parasites,  which  have  all  been  carefully  preserved,  but  not,  as 
yet,  carefully  studied.  It  is  not  even  known  how  many  species  are 
represented  in  the  assortment,  which  includes  a  considerable  number 
of  undescribed  forms,  but  apparently  there  are  at  least  30,  and  prob- 
ably more,  from  Japan  alone.  Some  are  very  rare,  and  are  repre- 
sented by  but  a  few  individuals  among  the  thousands  which  have  been 
reared.  Others  are  common  at  times,  and  rare  or  absent  at  others. 
Some  few  are  generally  common,  and  practically  always  present. 

The  considerable  shipments  of  cocoons  which  were  collected  in 
Russia  by  Prof.  Kincaid  and  forwarded  to  the  laboratory  in  1909 
were  invariably  so  long  en  route  as  to  permit  the  Apanteles  to  issue 
and  die,  but,  as  in  the  case  of  the  Japanese  shipments,  the  secondary 
parasites  did  not  suffer.  Not  nearly  so  much  material  of  this  sort 
has  been  received  from  European  sources,  and  probably  on  that 
account  alone  the  variety  of  secondary  parasites  reared  has  not  been 
so  large.  Nevertheless,  more  than  20  species  have  been  recog- 
nized and  probably  at  least  25  have  been  reared  in  varying  abund- 
ance. 

A  good  many  of  these  secondary  parasites  have  a  very  close  resem- 
blance to  those  which  have  been  reared  from  the  Japanese  material. 


iwkasitks  OF  GIPSY-MOTH  CATERPILLARS. 


199 


In  some  instances  they  appear  to  be  identical.  In  others  it  may  be 
possible  to  find  minor  structural  characters  which,  together  with  the 
difference  in  their  habitat,  will  make  it  worth  while  to  designate  them 
by  different  names.  Some  very  distinct  species  are  peculiar  to 
Europe  or  to  Japan,  and  remain  unrepresented  by  any  nearly  resem- 
bling them  in  the  other  country. 

In  1909,  as  the  immediate  result  of  colonization  work  carried  out 
under  the  happy  auspices  already  described,  it  was  possible  to 
collect  large  numbers  of  Apanteles  fulvipes  cocoons  under  perfectly 
natural  conditions  in  the  open  in  America.  This  was  accordingly 
done,  with  the  result  that  no  less  than  IS  additional  hyperparasites 
were  added  to  the  list  of  those  which  attacked  this  host.  Some  of 
these  were  rare,  others  very  common  in  this  connection.  A  few 
appear  to  be  undescribed. 

The  most  interesting  tiling  about  them  taken  as  a  group,  is  the 
general  resemblance  which  they  bear  to  the  similar  groups  of  Euro- 
pean and  Japanese  parasitic  Hymenop- 

tera  having  identical  habits.  Appa- 
rently there  are  about  as  man)  points 
in  common  bet  w  ecu  t  he  American  para- 
site- of  A  pa  lit  ( 1 1  sfulrijh  s  in  id  the  Japa- 
nese or  the  European  as  there  are  be- 
tween the  European  and  the  Japanese. 

In  the  course  of  the  work  a  total  of 
.r),4")()  cocoons  of  .1  jxutft  U  sj'ulrijH  s  w  as 
collected  from  several  of  the  recently 
established  colonies,  but  principally 
from  two,  representing  the  first  among  Fi<;..n.  -Apain<ic.<  fuiripcs:  Coooonsfrom 
those  planted  in  1909  and  in  both  of      Nvl;irh  M»ntelea  and  its  secondaries 

1  .  .  have  issui'il.  as  follows:  a,  A pantcles  ful~ 

winch  a  second  generation  occurred.  nipt,-  b,  Hypopteramahis;  e,  HemiUUs 
Of  this  total,  1,531,  or  28  per  cent,  had  s'' :  d-  DHwaehys;  <.  decodes.  En- 
produced  the  Apanteles  at  the  time  01 

collection;  2,378,  or  44  per  cent,  were  attacked  by  secondaries  (fig. 
34);  634,  or  12  per  cent,  were  destroyed  by  various  predatory  insects, 
ants,  etc.;  and  91S,  or  1 7  per  cent,  remained  unhatched  in  October, 
1909.  Among  the  unhatched  cocoons  was  a  considerable  proportion 
which  contained  the  hibernating  larva  of  Asecodes,  Elasmus,  and 
1  )immockia.  In  more  than  one  instance,  too,  hatching  was  prevented 
by  superparasitism,  and  in  others  death  probably  resulted  through 
the  attack  of  predatory  bugs.  On  at  least  one  occasion  Podisus  sp. 
was  found  with  its  proboscis  thrusl  through  the  wall  of  the  cocoon 
and  feeding  upon  the  parasite  larva  or  pupa  within. 

An  idea  of  the  variety  of  secondary  parasites  reared  is  conveyed 
by  tin4  tabulated  list  following. 


200  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


List  of  secondary  parasites  reared  from  American  cocoons  of  Apanteles  in  the  order  of  relative 

abundance. 


[In  this  list  the  number  of  individuals  of  Apanteles  killed,  not  the  gross  number  of  the  secondaries  reared, 
is  given.  In  case  of  tie,  the  species  which  was  relatively  the  more  important  in  the  particular  lot  or  lots 
from  which  it  was  reared  is  given  preference.] 


Hypopteromalus   1,  276 

Dibrachys   583 

Asecodes  

Hemi teles  No.  60  

Hemiteles  No.  61  

Hemiteles  No.  75  

Pezomachus  

Eulophid  

Hemiteles  No.  62  


161 

2  58 
52 

2  49 
64 
71 
18 


Pezomachus  No.  65. 
Pteromalid  No.  68  . 
Hemiteles  No.  63... 
Pteromalid  No.  70.. 

Eupelmus  

Hemiteles  No.  66... 
Anastatus  


15 
6 
5 
2 
2 
2 
1 


Total   2.288 


Local  conditions  as  affecting  the  control  of  this  parasite  through  hyperparasites 
were  well  represented  in  1909  by  a  comparison  between  the  relative  abundance  of  sec- 
ondary parasites  in  cocoons  from  two  colonies,  the  "  Reading-Wilmington,"  and  the 
"West  Manchester, "  which  were  planted  at  about  the  same  time.  In  both  repro- 
duction was  abundant,  and  a  large  number  of  cocoons  was  collected  from  each.  Only 
those  which  were  left  in  the  field  until  all  of  the  Apanteles  which  remained  healthy 
had  issued  are  counted  in  the  following: 


Reading-Wilming- 

West Manchester 

ton  colony. 

colony. 

Cocoons. 

Per  cent. 

Cocoons. 

Per  cent. 

Apanteles  

70 

8 

543 
Ki2 

66.  5 

Hyperparasites  

624 

68 

20 

Predators  

8 

1 

22 

2.5 

Unhatched  Oct.  20  

218 

23 

89 

11 

Total  

920 

816 

The  West  Manchester  colony  was  located  in  rather  dense  forest,  with  a  swamp 
partly  overgrown  with  brush  and  partly  with  thick  forest  on  one  side.  The  trees 
were  large,  and  cocoon  masses  were  frequently  far  beyond  reach.  Only  those  which 
could  be  reached  from  the  ground  were  collected.  There  were  more  cocoons  in  this 
colony  than  in  the  other,  but  they  were  not  quite  so  easily  collected.  It  is  of  course 
possible  that  the  larger  number  of  cocoons  explains  in  part  the  smaller  percentage  of 
hyperparasitism. 

The  increase  in  hyperparasitism  in  the  cocoons  of  the  second  generation  over  the 
first  can  only  be  demonstrated  in  the  case  of  the  West  Manchester  colony,  which  was 
the  only  one  where  there  was  a  second  generation  in  sufficient  abundance  to  permit 
of  adequate  field  collections.  In  this  it  is  or  appears  to  be  very  striking,  when 
the  fact  is  taken  into  consideration  that  a  considerable  number  of  parasites  hibernated 
in  the  cocoons  of  the  second,  while  none  were  found  in  those  of  the  first  which  failed 
to  hatch  after  the  1st  of  September. 


i  Many  Asecodes  remaining  unhatched  within  the  cocoons  will  doubtless  attempt  to  hibernate. 
'l  Hemiteles  NO.  (10  and  Hemiteles  \'o.  75  may  possibly  be  one  and  the  same  species.   It  is  possible,  too, 
that  further  study  will  cause  a  change  in  the  relative  position  of  the  two  species. 


I'AIIASTTES  OF  GTPSY-MOTH  CATERPILLARS. 


201 


Two  lots  of  each  generation  were  collected  after  the  healthy  parasites  had  issued, 
and  the  results  follow: 


First  generation. 

Second  generation. 

Cocoons. 

Per  cent. 

Cocoons. 

Per  cent. 

<il  \  ptapan%eles  

543 
Ifl 
22 
89 

66.5 
20 
2.5 
11 

636 
1.2!  17 

102 
»469 

26 
50 
4 

120 

Ilvperyiarasitcs  

Predators  

Unhatt-he<l  

Total  

8IG 

100 

2.-414  !  100 

'Oct.  20. 


Other  collections  of  cocoons  from  colonies  when'  the  A.pan  teles  was  liberated  too 
late  in  the  season  to  permit  of  two  generations  showed  a  high  rate  of  h yperparasit ism 
in  the  single  generation,  ac  tually  the  first  hut  corresponding  to  the  second.  Com- 
parison in  this  instance  is  valueless,  as  local  conditions  enter  in  which  can  not  be 
gauged. 

This  rather  lengthy  summary  of  a  study  in  by  per  parasitism  has 
been  prepared  and  is  here  presented  with  the  object  of  illustrating 
the  somewhat  modified  stand  which  it  lias  been  necessary  to  take 
concerning  the  subject  in  its  relation  to  the  project  of  parasite  intro- 
duction. Were  it  within  the  bounds  of  possibility  to  introduce  into 
America  the  parasites  of  the  gipsy  moth  (ApatUeUs  fulvipes,  for 
example)  without  introducing  the  secondary  parasites  which  preyed 
upon  them  abroad,  it  would  unquestionably  be  possible  to  secure  a 
greater  meed  of  efficiency  in  America  than  that  which  the  same  para- 
sites were  capable  of  attaining  in  their  native  countries.  This  is  on 
the  supposition  that  the  parasites  themselves  arc  no  more  likely  to  be 
attacked  by  the  American  by pcrparasites  than  their  hosts  are  likely 
to  be  attacked  by  the  American  primary  parasite-. 

That  the  assumptions  are  fallacious,  to  a  certain  extent,  is  well 
proved  by  the  results  following  the  temporary  establishment  here  of 
Apantdes  fulripes,  as  recounted  above,  and  that  the  same  results 
as  those  which  followed  the  exposure  of  this  parasite  to  American 
hyperparasites  will  result  in  the  instance  of  others  among  the  im- 
ported parasites  is  more  than  likely.  In  the  case  of  Compsilura 
concinnata  and  Apantdes  lacteicolor  Vier.  it  is  proved. 

The  truth  of  the  matter  is  that  the  secondary  parasites  are  very 
far  from  being  as  closely  restricted  to  one  or  two  species  of  hosts  as 
are  the  primary  parasites.  This  is  in  part  due  to  the  fact  that  they 
represent  for  the  most  part  a  much  more  degraded  form  of  para- 
sitism. Species  like  Dibrachys  boucheanus,  which  is  perhaps  as 
generally  abundant  and  omnivorous  as  any  of  the  parasitic  Ilymen- 
optera,  will  attack  anything  which  is  dipterous  or  hymenopterous, 
provided  it  is  physically  suitable  as  food  for  its  larvae.  Apantdes 
fulripes  and  caterpillar  parasites  generally  are  governed  in  their  host 


202 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


relations  by  physiological  rather  than  by  physical  limitations,  and 
the  difference  is  as  great  as  that  which  separates  the  true  predator 
from  the  true  parasite. 

Did  time  permit-,  and  were  this  the  proper  place,  a  lengthy  digres- 
sion might  be  made,  in  which  several  of  the  parasites  typical  of  both 
groups,  and  which  have  been  somewhat  carefully  studied  at  the 
laboratory,  could  be  compared,  the  better  to  give  strength  to  the 
statement  just  made.  A  little  later  attention  will  again  be  called  to 
the  matter. 

At  this  time  it  is  merely  desired  to  define  the  modified  stand  which 
it  has  been  necessary  to  take  upon  the  question  of  hyperparasites. 
It  is  no  longer  possible,  on  account  of  the  absence  of  their  secondaries, 
to  expect  a  much  if  any  greater  degree  of  efficiency  from  the  imported 
parasites  in  America  than  the  same  species  possess  abroad.  Since 
the  foreign  hyperparasites  of  the  gipsy  moth  are  generally  the  coun- 
terpart of  the  American  species,  which  will  become  hyperparasitic 
upon  the  gipsy  moth  just  so  soon  as  there  are  any  primary  parasites, 
their  introduction  could  not  possibly  do  more  than  result  in  the 
existence  in  America  of  a  somewhat  greater  variety  of  hyperparasites, 
which  as  a  group  would  play  exactly  the  same  role  as  the  lesser  variety 
now  existent  here.  Consequently  the  only  secondary  parasites  which 
we  have  to  fear  are  those  which  have  no  counterparts  in  America. 

That  such  exist  is  beyond  question;  that  they  are  in  the  minority 
is  equally  true.  The  only  species  which  have  been  recognized  as 
possibly  or  probably  falling  into  that  group  are  the  hyperparasites 
reared  from  the  gipsy-moth  eggs  from  Japan,  the  Melittobia  parasite 
of  tachinids;  the  eulophid  parasite  of  Pteromalus  egregius,  Perilarn- 
pus  cuprinus,  and  Ohalcis  fiskei;  and,  most  unfortunately,  two  primary 
parasites  already  introduced,  which  are  also  secondary,  Pteromalus 
egregius  and  Monodontomerus  sereus.  The  two  last  mentioned  are 
probably  both  beneficial  rather  than  noxious  in  the  final  analysis, 
but  nevertheless  both  are  peculiarly  adapted  to  act  as  secondary 
parasites  of  the  brown-tail  moth  better  than  as  secondary  parasites 
of  any  other  primary  host. 

It  is  not  intended  to  ignore  the  secondary  parasites  in  the  future 
any  more  than  in  the  past,  but  the  same  fears  which  have  been 
expressed  concerning  their  introduction  are  no  longer  felt  in  the 
same  manner,  and  the  benefits  which  were  formerly  expected  to 
accrue  through  their  exclusion  are  not  so  great  as  hoped. 

TACHINID  PARASITES  OF  THE  GIPSY  MOTH. 

In  proportion  as  one  after  another  of  the  previously  mentioned 
hymenopterous  parasites  of  the  gipsy  moth  have  been  eliminated 
from  the  lists  as  of  no  more  than  incidental  or  technical  interest,  and 
as  the  prospects  for  successfully  introducing  the  one  species  which 


TACHINTD  PARASITES  OF  THE  GIPSY  MOTH. 


203 


has  been  proved  to  be  of  preeminent  importance  abroad  have 
grOwn  less  bright,  the  taeliinid  parasites  have  gained  in  the  favor 
accorded  to  them,  and  from  being  considered  as  of  secondary  impor- 
tance they  have  become  of  primary  importance. 

This  change  in  attitude  toward  them  would  have  come  about  in 
another  way,  even  though  it  had  not  been  forced  through  the  compar- 
ative failure  of  the  hymenopterous  parasites  to  make  good  as  yet.  In 
nearly  every  instance  in  which  the  parasites  of  a  native  defoliating 
caterpillar  have  been  studied,  the  t  achinids  have  been  found  to  play  a 
part  which  was  at  Least  the  equivalent  <>f  the  part  taken  by  the 
Hvmenoptera,  while  in  more  than  half  the  instances  the  tachinids 

have  displayed  superior  efficiency.  This  is  probably  not  true  of 
the  parasites  of  any  other  order  than  the  Lepidoptera.  and  of  only  a 
portion  of  the  larger  representatives  of  that  order. 

For  the  most  part  the  tachinids  arc  restricted  in  their  choice  of 
lu»ts  through  purely  physiological  limitations,  but  to  a  materia] 
extent  they  are  restricted  through  purely  physical  causes  as  well. 
The  fall  webworm  offers  a  striking  example  of  both.  Literally 
thousands  of  taeliinid  parasites  have  been  reared  from  it  in  the 
course  of  t  he  past  few  years,  and  with  1  he  except  ion  of  an  insignificant 
number  of  the  imported  ( 'out  psihmi  COTldnnata,  only  a  single  species 
has  been  found  amongst  them  all.  This  species,  at  present  known 
as  Varichirta  aldrlc/ti,  through  its  habit  of  depositing  living  larva* 
upon  the  food  plant  instead  of  depositing  eggs  or  larva1  upon  the 
caterpillars,  possesses  a  very  distinct  and  powerful  advantage  in  its 

attack  upon  this  particular  host.  Lf  the  leaves  or  stems  near  a  colony 
of  young  caterpillars  are  selected  for  1  a rvi position,  it  is  practically  a 
certainty  that  the  caterpillars  will  enlarge  their  oesi  t<»  include 

these  leaves;  will  thereby  come  in  contact  with  the  parasite  larva*, 
and  thus  complete  the  chain  of  circu  mst  ances  through  which  para- 
sitism conies  about.  A  parasite  having  a  similar  habit  would  stand 
an  infinitesimal  show  of  providing  for  the  future  of  its  young  if  the 
webworm  should  suddenly  change  from  a  gregarious  and  nest 
building  to  a  solitary  and  wandering  insect.  At  the  same  time  that 
the  host  escaped  attack  by  Yaricha'ta,  it  would  lav  itself  open  to 
attack  by  a  variety  of  other  species  which  are  now  only  prevented 
from  attacking  it  on  account  of  the  protection  which  its  web  affords. 

But  even  though  it  were  freely  exposed  to  attack  by  all  the  species 
of  tachinids  which  deposit  eggs  or  lame  directly  upon  or  in  their  host, 
it  would  be  immune  to  such  attack  by  all  but  a  small  percentage  of 
the  species  which  might  conceivably  select  it  as  a  host.  This  is 
proved  through  the  occasional  occurrence  of  caterpillars  bearing 
t  achinid  eggs,  but  with  no  evidences  of  internal  parasitism  showing  on 
dissection.  It  is  not  merely  necessary  that  the  host  be  exposed  to 
attack  and  acceptable  to  the  instincts  of  the  mother  parasite;  it  is 


204  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

necessary  that  it  possess  certain  physiological  characteristics  which 
force  it  to  react  in  certain  ways  and  no  others  to  the  stimulus  of  the 
parasite's  presence.  Unless  the  host  does  react  in  the  manner  to 
which  the  parasite  is  accustomed,  the  parasite  which  is  unable  to 
accommodate  itself  to  circumstances  beyond  a  certain  extent  will 
find  itself  in  a  position  which  would  be  comparable  to  that  of  a  man 
suddenly  thrust  into  a  world  where  all  the  commonest  laws  of  nature  I 
worked  in  an  unfamiliar  manner. 

To  say  that  many  of  the  tachinids  are  physiologically  restricted  in  | 
their  host  relationships  is  equivalent  to  saying  that  they  are  restricted  | 
to  a  limited  number  of  hosts,  and  this  is  true;  probably  more  true 
than  of  the  hymenopterous  parasites  taken  as  a  whole,  or  of  any  large 
group  of  the  hymenopterous  parasites  if  the  Microgasterinae  and  a  few 
similar  groups  of  genera  are  excepted.  It  is  probably  true  also  that 
among  those  parasites  which  are  the  most  closely  restricted  in  their 
host  relationships  are  to  be  found  those  which  are  the  most  effective  in 
bringing  about  the  control  of  their  respective  hosts.  This  is  primarily 
due  to  the  fact  that  a  correlation  usually  exists  between  the  life  and 
seasonal  history  of  such  a  parasite  and  some  one  or  more  hosts  which 
it  is  particularly  fitted  to  attack.  The  existence  of  a  correlation 
between  parasite  and  host  of  such  intimate  character  makes  possible 
the  continued  existence  of  the  parasite  independently  of  alternate 
hosts,  and  it  is  thus  enabled  to  keep  pace  with  the  one  species  upon 
which  it  is  peculiarly  fitted  to  prey  when  other  circumstances  are 
favorable  to  its  increase. 

Some  of  the  most  interesting  examples  of  correlation  of  this  sort 
which  have  yet  come  to  attention  are  to  be  found  among  the  tachinid 
parasites  of  the  gipsy  moth  or  the  brown-tail  moth,  and  on  this  account 
as  well  as  on  a  purely  empirical  basis  they  are  now  considered  much 
more  likely  to  become  important  enemies  of  these  hosts  than  before 
their  characteristics  were  so  well  understood. 

THE    REARING  AND  COLONIZATION  OF  TACHINID   FLIES;   LARGE  CAGES 

VERSUS   SMALL  CAGES. 

In  more  ways  than  can  be  recalled  without  taking  up  and  discussing 
each  species  in  turn  has  the  necessity  for  a  more  complete  knowledge 
of  the  tachinid  parasites  impressed  itself  upon  those  most  concerned 
with  their  economical  handling.  The  difficulties  attending  the 
successful  hibernating  of  the  puparia  of  Blepharipa  and  the  myste- 
rious disappearance  of  Parexorista  chelonix,  after  it  was  considered 
to  be  thoroughly  established  in  America,  may  be  mentioned  as  con- 
spicuous examples  among  (he  ninny  oftentimes  curious  and  sometimes 
apparently  inexplicable  problems  which  have  come  up  for  solution. 
Just  at  the  present  lime  there  is  pressing  need  of  more  and  accurate 


Bui.  91,  Bureau  of  Entomology,  U.  S  Dept.  of  Agriculture. 


Plate  XIII. 


Bui.  91 ,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agriculture. 


Plate  XIV. 


Bui  91,  Bureau  of  Entomology  U.  S  Dept.  of  Agriculture. 


Plate  XV. 


View  of  Large  Cage  Used  in  1908  for  Tachinid  Rearing  Work.    From  Townsend. 


B*ul.  91,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agriculture. 


Plate  XVI. 


TACHINID  PARASITES  OF  THE  GIPSY  MOTH. 


205 


information  concerning  the  rapidity  of  dispersion  of  certain  anions: 
tln'M'  Hies  and  concerning  the  host  relations  of  certain  others. 

In  an  account  of  the  methods  used  in  conducting  investigations 
into  the  lives  and  habits  of  the  tachinids,  published  by  Mr.  C.  II.  T. 
Townsend  three  years  ago,  a  good  outline  of  the  beginning  of  this 
work  is  given.  It  has  been  found  necessary  to  modify  to  a  certain 
extent  the  methods  which  seemed  best  at  the  time  when  this  account 
was  written,  and  in  one  particular  at  least  it  seems  advisable  to 
correct  the  statements  therein  made  concerning  the  use  of  the  large 
out-of-door  rearing  cage  for  tachinid  reproduction  work  and 
investigation. 

In  the  beginning  the  use  of  the  large  cages,  consisting  of  a  wooden 
frame  covered  with  cloth  or  wire  screen  and  inclosing  a  living  tree, 
was  attempted  upon  a  considerable  scale.  Cages  of  this  character 
had  been  so  successfully  employed  in  various  somewhat  similar 
lines  of  work  as  to  justify  their  consideration  in  this,  and  accord- 
ingly a  dozen  or  more  were  constructed  and  used  for  the  confine- 
ment of  all  soils  of  introduced  enemies  of  the  gipsy  moth  or  the 
brown-tail  moth,  from  Ptenmaku  tgrtqWA  to  (alosoma  sycoplxanta, 
including  the  tachinid  parasites. 

The  first  of  them,  covered  with  wire  gauze,  was  constructed  in 
L905  (PI.  XIII)  and  has  been  figured  several  times  in  various  reports 
upon  and  accounts  of  the  work,  but  it  was  never  given  a  thorough 
test  on  account  of  the  failure  to  secure  parasites  in  any  amount  that 
hist  year.  In  1900  cheesecloth  coverings  were  subst  it  uted  for 
wire  and  a  number  of  cages,  the  general  pattern  of  that  figured 
herewith  (PI.  XIV),  was  constructed  and  used  that  year  and  in 
1907.  but  with  pretty  generally  unfavorable  results.  It  was  found 
that  only  a  very  small  number  of  caterpillars  could  be  supported 
by  the  foliage  of  the  inclosed  trees  or  shrubs,  and  that  it  was  neces- 
sary t<>  feed  them  artificially  exactly  aa  was  necessary  in  the  smaller 
cages.  The  impossibility  of  keeping  a  variety  of  native  insects  out, 
as  well  as  of  keeping  the  foreign  insects  in.  was  another  and  only 
too  apparent  fault,  hi  an  experiment  with  tachinid  reproduction 
in  one  of  these  cages  in  1907,  the  number  of  Hies  introduced  in  the 
beginning  grew  steadily  less  day  by  day,  with  no  adequate  explana- 
tion for  the  disappearance  of  the  mining  individuals. 

Another  disadvantage  accrued  through  the  fact  that  when  a 
caterpillar  was  in  any  way  dislodged  from  the  inclosed  tree  upon 
which  it  was  expected  to  remain  and  feed,  the  chances  were  infi- 
nitely greater  that  it  would  find  its  way  to  the  side,  and  then  to 
the  roof  of  the  cage,  than  that  it  would,  unassisted,  regain  its  former 
position.  The  parasites,  also,  instead  of  staying  about  the  tree 
where  their  business  was  supposed  to  demand  their  attention,  would 


206  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


persistently  remain  in  the  uppermost  recesses  of  the  cage  and  refuse  to 
come  down. 

All  in  all,  the  disadvantages  were  so  many,  in  proportion  to  the 
advantages,  and  these  latter  were  so  largely  imaginary  in  point  of  fact, 
as  to  result  in  the  decision  to  discontinue  the  use  of  the  large  cages 
entirely  in  1908. 

The  cage  figured  by  Mr.  Townsend  (PI.  XV)  was,  however,  an 
innovation  in  several  respects.  It  was  built  independently  of  any 
tree  winch  should  serve  as  food  for  the  inclosed  caterpillars,  but 
these  caterpillars  were  confined  within  certain  restricted  limits  and 
exposed  to  the  attack  of  the  tachinid  flies  at  one  and  the  same  time 
by  the  use  of  the  open  "tanglefooted  "  tray.  Here  a  most  distinct 
advantage  was  gained.  The  floor  of  trodden  earth  (subsequently 
replaced  by  cement)  effectually  prevented  the  entrance  of  numerous 
insects  which  were  formerly  uninvited  guests  and  thereby  removed 
another  serious  disadvantage.  An  arrangement  of  double  doors 
and  wire-screened  vestibule  prevented  the  untimely  liberation  of 
the  flies,  and  there  were  no  longer  so  many  inexplicable  disappear- 
ances. The  fact  that  the  top  of  the  cage  was  flat  instead  of  being 
extended  into  the  gable  tended  to  keep  the  flies  somewhere  more 
nearly  where  they  were  wanted.  In  short,  there  were  a  great  many 
advantages  possessed  by  the  new  cage  which  were  not  possessed  by 
the  old,  and  there  was  some  justification  for  considering  it  good. 

In  the  meantime  Mr.  Burgess,  who  had  taken  over  the  Calosoma 
work  in  the  fall  of  1907,  had  developed  the  out-of-door  cage  along 
totally  different  lines,  making  it  into  nothing  more  than  an  out-of- 
door  insectary  (PI.  XVI),  in  which  were  conducted  practically  all  of 
his  numerous  and  varied  investigations.  It  had  seemed  in  1907  as 
though  the  only  one  among  the  numerous  imported  insects  which 
had  done  at  all  well  in  the  out-of-door  cages  as  then  used  had  been 
the  Calosoma,  but  the  success  attending  their  use  for  the  rearing  of 
this  insect  was  so  soon  and  so  overwhelmingly  eclipsed  by  the  success 
which  attended  the  use  of  small  individual  cages  for  single  pairs  of 
the  beetles  or  individual  larvae  as  to  render  the  advisability  of  their 
discontinuation  for  this  purpose  emphatic. 

Some  attempt  was  made  to  use  the  tachinid  cage  in  1909,  but  not 
to  the  extent  to  which  it  had  been  used  the  previous  year.  Late 
in  the  summer  of  1909  reproduction  experiments  with  small  numbers 
of  various  species  of  tachinids  were  undertaken  by  Mr.  W.  11.  Thomp- 
son, who  used  cages  constructed  after  the  familiar  Riley  type,  but 
covered  entirely  with  coarse  fly  screen.  (PI.  XVII,  fig.  1.)  He 
succeeded  in  much  of  that  which  he  undertook  to  do,  and  in  1910 
continued  the  use  of  this  type  of  cage,  for  a  part  of  a  quite  extensive 
series  of  most  interesting  and  successful  experiments,  but  he  also 
used  a  much  smaller  cage  consisting  of  a  wire-screen  cylinder  (PI, 


TACHIXID  PARASITES  OF  THE  GIPSY  MOTH. 


207 


XVII.  fig.  2,  at  right),  about  8  inches  in  diameter  and  12  inches  high, 
with  wooden  top  and  bottom.  His  best  results  were  secured  through 
the  use  of  this  cylinder,  and  the  reason  appeared  to  be  that  the  flies 
were  less  likely  to  fly  and  acquire  sufficient  momentum  to  injure 
themselves  in  small  than  in  Large  cages. 

In  elaboration  of  the  principle  apparently  involved,  a  still  smaller 
cylinder  (PI.  XVII,  fig.  2,  at  left),  scarcely  3  inches  in  diameter  and 
shorter  than  that  formerly  used,  was  experimented  with.  Better 
results  than  ever  before  were  secured  upon  the  single  occasion  upon 
which  this  cage  was  used,  and  unless  further  experimentation  results 
in  additional  modifications  or  in  a  reversal  of  the  results  first  obtained, 
the  cvlinder  cage  figured  herewith  will  be  used  almost  exclusively 
in  1IM1. 

As  a  basis  for  comparison  of  the  utility  of  the  Large  versus  the 
small  cage-,  the  results  attending  (he  investigations  into  the  biology 
of  Blepharipa  may  be  taken  as  an  example. 

Between  300  and  400  Hies  were  used  in  an  attempt  to  secure 
oviposit  ion  ill  the  large  cage  iii  1908,  and  no  care  that  could  be  given 
them  under  these  conditions  was  lacking.  Not  a  single  female  com- 
pleted her  sexual  development  to  the  point  at  which  she  was  capable 
of  depositing  fertile  eggs,  and  no  eggs  of  any  sort  were  secured. 
Scores  instead  of  hundreds  of  flies  were  used  for  the  experiments 
in  the  spring  of  1910,  and  many  of  the  females  lived  throughout 
the  period  allotted  for  the  incubation  of  their  eggs  and  deposited 
them  at  the  rate  of  several  hundred  daily,  and  abundant  opportunity 

was  thus  aH'onled  for  the  continuation  of  the  studies  into  the  lives 
and  habits  of  the  young  larva?  under  dill'erent  conditions  and  in 
different  hosts. 

In  short  after  the  most  thorough  tests,  the  use  of  the  large  out-of- 
door  cages  has  been  definitely  abandoned  for  all  phases  of  the  work 
at  the  gipsy-moth  parasite  laboratory.  It  is  not.  however,  intended 
to  state  thus  dogmatically  that  similar  large  cages  would  not  be 
adaptable  to  work  with  parasites  of  any  other  host. 

ffYPERPAKASITES  ATTACKING  THE  TAGHHTHXB. 

Undoubtedly  there  is  abroad  an  important  group  of  secondary 
parasites  of  the  gipsy  moth  and  the  brown-tail  moth,  included  in 
which  are  some  which  attack  the  various  species  of  tachinids  to  such 
an  extent  as  indirectly  to  affect  the  welfare  of  the  primary  host. 
Very  little  is  known  of  this  hyperparasitic  fauna,  because  practically 
all  of  the  tachinids  received  have  been  from  host  caterpillars  which 
were  living  at  the  time  of  collection.  That  it  exists  is  well  indicated 
by  the  tentative  studies  of  the  American  parasites  of  Compsilura 
concinnata,  which  were  made  in  1910,  and  which  will  be  the  subject 
of  mention  at  another  place. 


208 


PARASITES  OF  GIPSY,  AND  BROWN-TAIL  MOTHS. 


Occasionally,  however,  a  few  secondary  parasites  have  been  reared 
from  puparia  from  abroad  either  because  these  puparia  were  col- 
lected in  part  in  the  open  or  because  the  parasites  were  of  species 
which  attacked  the  primary  parasite  during  the  life  of  the  primary 
host.  The  number  of  secondary  parasites  having  such  habit  is 
apparently  very  limited,  and  it  has  been  definitely  proved  of  but  two 
genera,  namely,  Perilampus  among  the  chalcidids  and  Mesochorus 
among  the  ichneumonids.  The  latter  has  never  been  reared  as  a 
parasite  of  any  tachinid. 

Because  of  the  rather  extraordinary  precautions  which  were  taken 
to  avoid  introducing  into  America  the  secondary,  together  with  the 
primary,  parasites  of  the  gipsy  moth  and  the  brown-tail  moth,  the 
whole  question  of  secondary  parasitism  is  worthy  of  considerable 
attention  in  anything  which  purports  to  be  a  history,  however 
abbreviated,  of  the  operations  conducted  at  the  parasite  laboratory. 
In  the  case  of  those  attacking  the  tachinids  it  is  better  that  they  be 
briefly  considered  en  masse,  since  there  are  very  few  among  them 
with  host  relations  restricted  other  than  physically. 

Perilampus  cuprinus  Forst. 

Actually,  only  a  very  little  is  known  of  this  species  from  first-hand 
investigations  further  than  that  it  is  occasionally  reared  from  puparia 
of  any  species  of  tachinid  parasitic  upon  the  browmtail  moth  or  gipsy 
moth  in  Europe,  and  under  circumstamces  which  strongly  indicate 
a  habit  of  making  its  attack  before  the  death  of  the  primary  host. 
At  the  same  time  it  is  felt  that  much  is  known  of  the  probable  habits 
of  this  species  through  analogy  as  the  results  of  Mr.  Smith's  studies 
of  the  early  history  of  the  allied  American  species,  Perilamjms 
hyalinus  Say,  which  attacks  the  parasites,  both  hymenopterous  and 
dipterous,  of  the  fall  webworm.  Presumably,  like  the  American 
species,  its  minute  first-stage  larva,  or  ^planidium,"  gains  access  to 
the  host  in  some  maimer  not  quite  clear,  and  after  wandering  about 
in  its  body  for  a  time  enters  the  bodies  of  such  parasites  as  it  chances 
to  encounter. 

That  a  secondary  parasite  having  such  habits  might  be  expected 
to  be  peculiarly  a  parasite  of  the  parasites  of  one  particular  host 
rather  than  of  the  same  or  similar  parasites  of  another  host,  coupled 
with  the  fact  that  extraordinary  precautions  were  obviously  necessary 
to  provide  against  its  accidental  importation,  made  Perilampus 
cuprinus  appear  peculiarly  abhorrent,  and  for  a  time  following  the 
discovery  of  the  early  habits  of  P.  liyalinus  precautions  against  (he 
importation  of  its  congener  were  redoubled.  In  the  course  of  time  it 
was  determined  that  it  was  never  present  in  sufficient  abundance 
to  make  it  at  all  probable  that  it  was  a  parasite  of  the  gipsy  moth  or 
the  brown-tail  moth  parasites  to  anything  like  the  extent  to  which 


TACHINID  PARASITES  OF  THE  GIPSY  MOTH. 


209 


P.  hyalinus  was  thus  peculiarly  an  enemy  of  fall  webworm  parasites, 
and  thus  a  friend  of  the  fall  webworm.  Neither,  when  it  was  present 
(which  it  was  not,  as  a  rule) ,  was  it  ever  known  to  emerge  from  infested 
puparia  of  the  "summer  issuing  species"  until  long  after  the  flies 
had  ceased  to  emerge.  From  the  puparia  of  species  which  hiber- 
nated as  pupae  it  never  emerged  until  the  spring  and  then  appeared 
before  the  flies  themselves.  It  was  thus  possible  to  provide  against 
its  escape  with  little  trouble,  and  it  is  now  considered  as  distinctly 
less  menacing  than  the  species  which  follows. 

Melittobia  acasta  Walk. 

Another  most  extraordinary  parasite  of  tachinids  in  Europe  is 
Melittobia  aca sta,  according  to  a  determination  furnished  some  years 
ago  by  Dr.  Ashmead.  It  is  thought  probable  that  a  careful  com- 
parison between  the  parasite  of  the  tachinids  and  If.  acasta  will 
reveal  specific  difTerences,  but  at  the  time  of  wrii  ing  such  comparison 
has  not  been  made.  Of  all  of  the  secondaries  which  have  been 
imported  with  the  parasite  material  this  has  proved  tin4  most 
annoying. 

Its  most  annoying  characteristic  its  minuteness,  which  enables 
it  to  pass  through  50-mesh  wire  screen  at  will,  and  this,  coupled  with 
an  extreme  hardiness  and  an  insidious  inquisitiveness  which  seems 
to  know  no  bounds,  has  resulted  upon  two  occasions  in  an  infestation 
of  the  laboratory  which  is  comparable  to  a  similar  infestation,  which 
will  receive  further  mention,  by  the  mite  Pediculoides. 

No  one  knows  where  it  came  from  upon  either  occasion  or  how  it 
first  succeeded  in  gaining  a  foothold  in  the  laboratory.  Its  first 
appearance  was  in  1006,  when  Mr.  Tims  encountered  it  in  several 
lots  of  puparia  of  different  species  of  tachinids  from  several  Kuropean 
localities.  Mr.  Titus  evidently  thought,  judging  from  his  notes, 
that  it  had  been  imported  in  each  instance  with  the  material  from 
those  localities.  lie  studied  its  habits  that  first  year,  and  found 
that  it  would  oviposit  freely  in  confinement  and  that  such  oviposit  ion 
was  successful.  He  did  not  give  it  full  credit  for  its  insidiousness,  and 
as  a  result  it  succeeded  in  eluding  his  vigilance  and  gaining  access 
to  a  number  of  the  lots  of  hibernating  puparia  of  Blepharipa,  upon 
which  it  reproduced  with  great  freedom. 

In  the  spring  of  1907  this  circumstance  became  evident  through 
its  emergence  in  some  numbers  from  several  of  the  lots  of  hibernating 
puparia  early  in  June,  after  most  of  the  flies  had  issued.  An  examina- 
tion of  the  remaining  puparia  was  thereupon  undertaken  and  a  vast 
number  of  larvae,  pupae,  and  unissued  adults  destroyed. 

At  that  time  it  was  supposed  that  each  of  the  lots  of  puparia  were 
infested  at  the  time  of  their  receipt,  but  when  an  even  larger  amount 

\)50T7°— Bull.  1)1—11  14 


210  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

of  similar  material  was  received  from  an  even  greater  number  of 
localities  in  1907,  and  a  smaller,  but  still  a  considerable  amount  in 
the  course  of  the  year  following,  and  no  trace  of  Melittobia  was 
encountered,  it  began  to  become  apparent  that  the  quite  general 
infestation  of  the  puparia  in  1906  had  taken  place  after  their  receipt 
at  the  laboratory. 

Vigilance  unrewarded  during  the  two  years  slackened  somewhat 
in  1909,  and  late  in  the  summer  a  new  infestation  of  Melittobia 
suddenly  developed.  Where  it  originated  was  and  remains  wholly  a 
mystery.  Possibly  the  first  individuals  were  received  in  a  large 
shipment  of  sarcophagid  puparia  which  had  been  collected  in  Russia 
and  forwarded  to  the  laboratory  by  Mr.  Kincaid,  who  considered 
them  to  be  gipsy-moth  parasites.  This  lot  of  several  thousand 
puparia  was  thoroughly  infested,  and  a  very  large  proportion  con- 
tained either  the  exit  holes  or  the  brood  of  Melittobia  when  their 
condition  was  discovered. 

But  the  infestation  did  not  stop  here.  Various  small  lots  of  puparia 
of  various  sorts,  inclosed  in  small  pasteboard  boxes,  in  cloth-covered 
vials,  or  in  other  receptacles  were  found  to  have  been  attacked  by 
the  parasite.  It  seemed  suddenly  to  have  come  from  nowhere  and 
to  have  attacked  everything  at  once. 

Avery  general  cleaning  up  was  immediately  instituted,  but  again, 
it  was  felt,  after  the  damage  had  been  done.  The  sarcophagid 
puparia,  which  would  otherwise  have  served  as  the  basis  for  a  very 
necessary  and  desirable  series  of  investigations  into  the  true  char- 
acter of  these  flies,  had  to  be  destroyed.  A  large  percentage  of 
them  was  attacked  by  the  parasite,  and  the  rearing  of  the  healthy 
remainder  involved  the  isolation  of  each  and  all  of  them  in  a  series 
of  tightly  stoppered  vials.  The  Melittobia  were  issuing  daily  and 
immediately  attacking  the  healthy  remainder  and  there  was  no 
method  short  of  breaking  open  each  puparium  which  sufficed  to 
determine  its  condition. 

After  the  cleaning  up  had  been  accomplished,  Mr.  Smith  began  a 
series  of  investigations  into  the  life  and  habits  of  the  parasite,  the 
results  of  which  he  intended  to  have  prepared  for  publication  before 
leaving  the  laboratory.  Since  he  did  not  do  this,  and  since  the 
species  is  one  which  is  likely  to  become  a  cause  of  annoyance  should 
similar  work  to  the  present  be  undertaken,  the  following  brief  sum- 
mary of  the  results  of  his  studies  may  be  given. 

The  minute  females,  after  having  been  fertilized  by  the  still  more 
minute,  blind,  and  wingless  males,  issue  from  the  puparium  in  which 
they  have  passed  their  early  transformations  and  go  in  quest  of  others 
which  they  may  attack.  They  will  also  attack  hymenopterous  co- 
coons, but  with  less  success,  apparently,  than  in  the  case  of  the  more 
favored  bost.     In  the  course  of  this  search  they  will  enter  the  damp 


TAClilXID   PA  HAS  IT  KS  OF    IT  I  K  (ilPSY  MOTH. 


211 


earth  for  a  distance  of  several  inches  in  quest  of  puparia  which  have 
been  buried  therein,  and  since  they  can  pass  through  well-nigh  invis- 
ible cracks  and  are  in  possession  of  an  acute  maternal  instinct,  they 
are  able  to  enter  receptacles  of  all  sorts  by  means  of  openings  far  too 
small  to  permit  the  passage  of  any  other  among  the  secondary  para- 
sites which  have  been  studied,  not  excepting  those  from  the  gipsy- 
moth  eggs. 

Having  located  their  prey,  oviposition  follows,  the  eggs  are  de- 
posited upon  the  surface  of  the  nymphs  in  an  irregular  circle  sur- 
rounding a  wound  made  by  the  ovipositor.  They  are  very  small  but 
appear  to  swell  somewhat  before  hatching,  and  if  the  puparium  is 
broken  open  so  that  they  are  freely  exposed  to  the  air,  they  will  not 
hatch  at  all.  Contrary  to  expectations  the  larva?  and  their  mode  of 
life  presented  nothing  abnormal.  The  number  of  lame  or  pupa* 
which  had  been  found  in  the  hibernated  Blepharipa  in  the  spring  of 
1907  was  so  extraordinarily  large  in  comparison  to  the  size  of  the 
mother  insect  that  it  was  Considered  likely  that  some  form  of  polyem- 
bryony  or  pa»dogenesis  would  be  found  upon  further  study. 

Becoming  full  fed.  t  hey  will  pupate  immediately  if  t  he  temporal  ure 
is  uniformly  high,  but  will  hibernate  if  it  is  allowed  to  fall  below  a 
point  which  was  not  determined.  As  BOOB  as  pupation  has  taken 
place  t  lie  sexes  are  easily  separable,  through  t  he  absence1  of  wings  and 
eves  in  the  males.  The  male  pupa1  develop  much  more  rapidly  than 
t  he  females  and  the  adults  issue  in  advance  of  t  heir  mates.  They  are 
invariably  in  t  he  great  minority,  and  t  heir  ,-elat  ive  numerical  strength 
is  still  further  reduced  through  the  terrific  duels  which  follow  their 
emergence.  Notwithstanding  their  physical  defects  in  the  matter  of 
sight  and  powers  of  (light,  their  seeming  weakness  otherwise,  and 
their  small  size,  even  when  compared  to  their  mates,  they  possess  a 
courage  and  a  vigor  that  is  most  surprising.  In  the  instance  of  a 
colony  which  had  been  removed,  from  the  puparium  in  which  it  was 
reared  through  its  early  stages,  to  a  small  glass  cell,  the  several  males 
which  issued  well  in  advance  of  the  females  engaged  fort hwith  in  con- 
flict, in  the  course  of  which  a  considerable  number  was  killed.  The 
survivors  of  this  Lilliputian  battle  royal  calmly  awaited  the  issu- 
ance of  the  members  of  their  harems  and  proceeded  to  mate  wit  It  one 
and  all  with  an  ardor  which  seemed  to  know  DO  limit. 

Mr.  Smith  also  conducted  an  experiment  in  parthenogenesis,  the 
results  of  which  were  and  remain  unique  in  the  annals  of  the  labora- 
tory. As  in  every  other  instance  in  which  an  attempt  has  been  made 
to  secure1  pari  henogenel  ic  reproduction  with  the  hymenopterous  para- 
sites, it  was  successful,  but  in  this  case. to  a  limited  degree  only,  in 
that  the  females  positively  refused  to  deposit  more  eggs  than  they 
would  normally  have  produced  males  had  they  been  properly  fertilized. 
Instead  of  depositing  sufficient  to  provide  for  the  complete  consump- 


212 


PAEASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


tion  of  the  host,  only  four  or  five  would  be  deposited  at  a  time,  and 
notwithstanding  that  after  the  depositing  of  what  probably  amounted 
to  barely  5  per  cent  of  those  which  filled  their  abdomens  fairly  to 
bursting,  they  ceased,  and  nothing  short  of  impregnation  served  to 
arouse  their  maternal  instincts  again.  As  virgins  they  displayed  a 
longevity  lacking  in  the  case  of  the  fertilized  individuals,  and  in  those 
instances  in  which  they  were  properly  cared  for  easily  outlived  the 
time  necessary  for  their  scanty  progeny  to  complete  its  transformation. 

This  progeny,  as  was  expected,  was  exclusively  of  the  male  sex, 
which,  when  afforded  opportunity,  promptly  united  with  their  virgin 
mothers,  who  thereupon  displayed  the  normal  desire  to  deposit  their 
eggs.  As  in  the  instance  of  Schedius,  the  fruit  of  such  unnatural 
union  consisted  of  both  sexes. 

Nothing  approaching  this  characteristic  of  Melittobia  has  been 
encountered  in  any  similar  studies  which  have  been  made  of  the  par- 
thenogenetic  reproduction  of  the  parasitic  Hymenoptera.  In  every 
instance  either  one  sex  or  the  other  has  been  the  result,  and  oviposi- 
tion  by  virgin  mothers,  in  so  far  as  any  observations  to  the  contrary 
have  been  made,  is  perfectly  normal  and  as  free  as  by  mated  females. 

It  formed  a  strong  argument  in  favor  of  the  sex  of  the  egg,  in  tins 
particular  species,  having  been  determined  before  fertilization  took 
place,  a  characteristic  which  is  certainly  not  possessed  by  the  majority 
of  the  parasites  studied. 

Chalcis  fiskei  Crawf. 

This  large  and  fine  representative  of  its  genus  has  been  received 
from  Japan  each  year  since  the  first  large  shipments  came  from  that 
country  in  1908  as  a  parasite  of  Crossocosmia  and  Tachina.  It  is  of 
interest  in  that  it  is  fairly  common,  and  worthy  of  consideration  on 
that  account,  but  more  on  account  of  its  having  been  reared  under 
circumstances  winch  tend  to  indicate  that  it  somehow  gains  access  to 
the  tachinid  larva  before  the  latter  leaves  its  host.  This  evidence  is 
not  sufficiently  complete  to  justify  an  outright  statement  to  the  same 
effect,  but  it  is  sufficiently  convincing  to  make  its  possibility  worthy 
of  mention.  On  this  account  the  species  acquires  an  importance 
which  it  would  otherwise  lack,  and  as  a  possible  specific  enemy  of  the 
parasites  of  the  gipsy  moth  it  is  worthy  of  special  endeavors  looking 
toward  its  exclusion. 

MONODONTOMERUS  ^REUS  WALK. 

As  will  be  mentioned  again  under  the  discussion  of  this  species  as 
a  primary  parasite  of  the  gipsy  moth  and  the  brown-tail  moth,  Mono- 
dontomerus  is  commonly  reared  as  a  secondary  as  well  as  a  primal y 
parasite.  Its  occurrence  as  a  secondary  is  altogether  too  frequent 
and  under  such  conditions  as  to  make  its  recognition  as  such  too  plain 
to  permit  excuses  in  its  behalf  similar  to  those  which  have  been  put 


TAC IITXTD  PARASITES  OF  THE  GTPSY  MOTH. 


213 


forward  in  the  case  of  Theronia  fulvescens  Cress.  It  is  therefore  con- 
si.  leied  as  a  secondary  just  as  much  and  as  habitually  as  it  is  a  primary 
and  the  question  as  to  whether  it  is  of  enough  more  importance  in 
one  role  than  it  is  in  the  other  to  render  it  more  than  neutral  remains 
to  be  decided.  Apparently  its  value  as  a  primary  is  sufficient  to 
render  void  its  noxiousness  as  a  secondary,  and  to  leave  a  consider- 
able margin  to  its  good,  but  this  margin  does  not  seem  quite  as  wide 
now  as  it  did  a  year  ago,  and  it  will  require  a  year  or  two  more  to 
determine  the  tine  status  of  the  parasite. 

Miscellaneous  Parasites. 

There  are  quite  a  number  of  small  ehaleidids.  the  most  of  them 
being  Dihraclnis  bnuclmittus  Hat z.  which  are  occasionaHj  received 
with  shipments  of  t  achinids 
from    abroad.     None  of 

them  i>  of  any  importance 
whatever  in  this  connec- 
tion, from  the  point  of 
view  gained  through  the 
st  udy  of  t  he  material  col- 
lected and  sent  under  the 
condit  ions  which  have  pre- 
vailed in  the  past.  Some- 
times when  lots  of  loose 
puparia  have  been  shipped 
as  such,  loosely  packed, 
two  or  three  among  them 
have  produced  a  colony  of 
Dibrachys  or  some  other 
parasite  of  similar  size  and 
habits,  and  these  individ- 
uals have  immediately  set 
about  the  propagation  of 
their  species  with  such  good  efl'ect  as  to  bring  about  the  destruction 
of  the  larger  part  of  the  remaining  puparia. 

No  serious  effort  has  as  yet  been  made  to  sort  the  Chalcidida*  thus 
reared  to  species,  much  less  to  determine  their  specific  identity. 


Fig.  Zo.—Blepharipa  scuiellata:  Adult  female. 

(Original.) 


Enlarged. 


BLEPHAKTPA  BCUTELLATA  DESV. 

Among  t  he  t  achinid  parasites  of  the  gipsy  moth  caterpillars  or  the 
brown-tail  moth  caterpillars,  Blepliaripa  scutellata  (fig.  35)  is  the 
most  conspicuous  representative  of  the  group  characterized  by  the 
habit  of  depositing  eggs  (figs.  36  and  37)  upon  the  foliage  of  trees  or 
other  plants  frequented  by  its  host  with  the  deliberate  intention  that 
they  shall  be  devoured.    It  is  also  an  exceedingly  close  ally  to  the 


214 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Fig.  M— Blepharipa  scutellata: 
Eggs  in  situ  on  fragment  of 
leaf.  Enlarged.  (Original.) 


known. 


Japanese  Crossocosmia  sericarix,  which  was  the  subject  of  the  original 
investigations  by  Dr.  Sasaki  through  which  this  peculiar  habit  was 
discovered.  The  full  life  of  the  fly  from  the  deposition  of  the  eggs  to 
the  issuance  of  the  adult,  some  10  or  1 1  months  later,  has  been  the  sub- 
ject of  a  special  series  of  investigations  by  Mr.  W.  R.  Thompson,  who, 
it  is  expected,  will  shortly  publish  the  results  of  his  studies. 

It  is  worthy  of  note  that  the  results  of  Dr. 
Sasaki's  observations  have  been  abundantly 
confirmed  in  very  nearly  every  respect  in  which 
there  is  not  an  actual  difference  between  the 
habits  of  Blepharipa  and  those  of  Crossocosmia. 
Each  female  fly  is  capable  of  depositing  sev- 
eral thousands  of  eggs  upon  the  foliage  of  trees 
frequented  by  the  caterpillars  of  the  chosen 
host,  but  it  is  not  known  to  what  extent  she 
employs  discretionary  powers  in  the  selection 
of  these  trees.  Presumably  she  is  attracted 
to  those  upon  which  the  host  caterpillars  are 
most  abundant.  Whether  one  sort  of  tree  is 
more  attractive  to  them  than  another  is  not 
The  young  larvae  hatching  from  the  eggs  which  have 
escaped  maceration  by  the  mandibles  of  the  caterpillars  pass  through 
the  wall  of  the  alimentary  canal  and  immediately  proceed  to  take 
full  advantage  of  the  physiological  changes  brought  about  in  the 
host  organism  as  the  direct  result  of  their  presence.  There  are  two 
larval  ecdyses  and  three  larval  stages  (as  is  the  case  with  every  other 
parasite  of  which  the  transfor- 
mations are  sufficiently  well 
known  to  make  any  statement 
possible),  and  the  manner  of  life 
undergoes  a  change  with  each 
ecdysis. 

The  first-stage  larva  embeds 
itself  in  the  tissues  of  the  host, 
which  apparently  react  jn  a  man- 
ner somewhat  suggestive  of  the 
reaction  which  results  in  the 
growth  of  a  vegetable  gall  fol- 
lowing attack  by  a  gall-making 
insect.    The  drawings  of  these 

gall-like  bodies  containing  the  larvae  (fig.  38),  as  well  as  the  drawings 
of  the  egg  and  of  the  second-stage  larval  "funnel"  were  prepared 
under  the  direction  of  Mr.  Thompson  as  illustrations  for  his  forth- 
coming paper. 

The  second-stage  larva  undergoes  a  complete  change  in  its  manner 
of  life,  and  its  activities  result  in  the  formation  of  a  tracheal  "funnel," 


Fig.  37.— a,  Egg  of  Blepharipa  scutellata,  showing 
characteristic  sculpture  and  markings;  b,  egg  of 
Pales  pavida.   Greatly  enlarged.  (Original.) 


TACHIXID  PARASITES  OF  THE  GIPSY  MOTH. 


215 


as  illustrated  in  (inures  and  40.  In  this  stage  the  larva  breathes 
through  the  spiracle  of  its  host,  to  which  the  "funnel,"  which  is 
apparently  formed  by  the  adventitious  growth  of  a  main  branch  of 
the  trachea,  is  directly  attached. 

But  few  of  the  parasites,  the  early  stages  of  which  have  been  studied 
at  the  laboratory,  exhibit  a  more  clearly  defined  physiological  rela- 
tionship with  their 
host  than  does  Ble- 
pharipa.  This  re- 
lationship is  com- 
parable in  many 
ways  to  that  be- 
tween the  cynipid 
gall-makers  and  the 

oak  tree  which 
serves  as  t  heir  host . 

As  is  well  known, 

many  species  of  cy- 

nipicLs  are  closely 
restricted    to  one 

Species  of  Oak,  Or,  Fi<;.  Ifc-iBffjAaHpi  teuttttata.  Pbst-Stafe  larvae:  o,  Natural  size;  6, 
at    least    to  Several       greatly  enlarged;  c.c.r.  great lj  enlarged  in  situ  In  atrophied  tissue  of 

.         ...    ,         '         host.  (Original.) 
nearly    allied  spe- 
cies, and  the  same  is  t<»  be  expected  of  parasites  like  Blepharipa  and 
others  here  spoken  of  as  physiological,  and  thus  limited  in  their  host 
relationships.     The  gipsy  moth  itself  is  comparable  to  the  parasites 

in  which  the  host 
relations  are  deter- 
mined by  physical 
rather  than  by 
physiological  con- 
ditions. In  its 
choice  of  food,  al- 
though it  prefers 
oak  to  almost  any 
other  of  the  native 
trees,  it  can  and 
does  attack  all  or 
nearly  all  varieties 
of  deciduous  trees,  and  even  conifers  and  herbaceous  plants  when 
necessity  demands. 

The  development  of  the  Blepharipa  is  directly  correlated  to  the 
development  of  the  host,  and  as  a  parasite  of  the  gipsy  moth,  its 
larva  awaits  the  pupation  of  the  host  before  assuming  the  aggressive, 
and  destroying  it  (PI.  XVIII,  fig.  1).  Its  own  pupation  is  accom- 
plished in  the  earth  (PI.  XVIII,  fig.  2),  and  the  pupa  develops  adult 


Fig.  SV.—Blephari/Hi  taUt  Jlaki:  Second-stage  larva  hi  situ  in  a  portion  of 
its  tracheal  "  funnel."    Greatly  enlarged.  (Original.) 


216 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


characters  in  the  fall.  The  space  between  the  pupa  or  nymph  and 
the  shell  of  the  puparium  is  filled  by  a  small  quantity  of  liquid,  and 
the  complete  drying  up  of  this  liquid  is  very  prejudical  to  the  health 
of  the  individual,  and  is  usually  sufficient  to  prevent  its  emergence. 

The  difficulties  which  have  stood  in  the  way  of  a  successful  intro- 
duction of  BlepJiarijm  scutellata  into  America  have  differed  in  many 
respects  from  those  which  have  accompanied  the  work  with  any  of 
the  other  species,  saving  only  the  closely  allied  Crossocosmia.  The 
first  importations  of  full-grown  caterpillars  or  freshly-formed  pupae 
of  the  gipsy  moth  in  1905  resulted  in  the  securing  of  a  considerable 
number  of  hibernating  pup  aria.  There  were  several  hundred  at  least, 
but  although  they  were  kept  under  conditions  which  would  be  satis- 
factory in  the  case  of  most  of  the  tachinids,  not  a  single  Blepharipa 
issued  in  the  spring  of  1906.    The  death  of  the  insect  did  not  take 


cent  emergence  from  a  total  of  5,000  was  secured.  The  year  before 
they  were  also  hibernated  in  earth,  but  the  emergence  was  less, 
amounting  to  only  3  per  cent  of  the  total,  and  the  year  following 
still  less,  being  only  about  1  per  cent. 

In  1909  for  the  first  time  since  the  inception  of  the  work  large  num- 
bers of  living  gipsy-moth  pupae  containing  the  immature  maggots  of 
Blepharipa  were  received  at  the  laboratory  from  Hyeres,  France, 
through  the  magnificent  efforts  of  M.  Kene  Oberthiir,  of  Rennes,  and 
as  a  direct  result  of  the  senior  author's  trip  earlier  the  same  year. 
Some  idea  of  the  size  of  these  shipments  may  be  gained  by  reference 
to  Plate  XIX,  figures  1  and  2,  which  show  a  small  proportion  of  the 
toi  al  number  of  packages  at  the  time  of  their  receipt  at  the  laboratory. 
For  the  first  time  it  was  possible  to  allow  the  formation  of  the  puparia 
under  natural  conditions  in  the  earth.  During  each  of  the  preceding 
years  the  caterpillars  and  pupse  had  been  received  from  abroad  by 
means  of  the  ordinary  methods  of  transportation  and  puparia  had 
been  formed  in  the  boxes  on  receipt.  They  were  often  injured  and 
always  thoroughly  dried. when  received.    This  year  provision  had 


place  until  after  the  fly  was 
fully  formed  and  apparently 
nearly  ready  to  issue  from  the 
puparium. 


Fig.  40.— Blepharipa  scutellata:  Basal  portion  of  tracheal 
"funnel."    Greatly  enlarged.  (Original.) 


A  great  many  different 
methods  of  hibernating  these 
puparia  have  been  experi- 
mented with  at  the  laboratory 
with  variable,  and  until  the 
winter  of  1909  with  poor,  re- 
sults. During  the  winter  of 
1907-8  the  puparia  were  kept 
in  moist  earth  and  a  10  per 


Bui.  91,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agricultui 


Plate  XVIII. 


Fig.  2.— Blepharipa  scutellata:  Puparia.  Slightly  Enlarged. 
(Original.) 


Bui.  91,  Bureau  of  Entomology,  U.  S  Dept.  of  Agricu 


Plate  XIX. 


Fig.  2.— Importation  of  Gipsy-Moth  Caterpillars  from  France  in  1909;  Receipt 
at  Laboratory,  Melrose  Highlands,  Mass.  ^Original.) 


TACHIXID  PARASITES  OF  THE  GIPSY  MOTH. 


217 


been  made  for  cold  storage  in  transit,  with  the  results  as  mentioned 
above. 

A  very  large  number  of  the  parasites  were  secured  in  this  manner, 
and  several  thousands  of  the  maggots  were  allowed  to  enter  the  earth 
in  the  open  in  forests  infested  by  the  gipsy  moth.  Others  were  allowed 
to  pupate  in  a  natural  manner  in  forest  soil  or  in  a  mixture  of  garden 
loam  and  sand  in  a  variety  of  containers  in  the  Laboratory  grounds. 

An  examination  of  these  puparia  was  made  from  time  to  time  dur- 
ing the  winter  and  they  were  found  to  be  uniformly  in  a  much  more 
satisfactory  condition  than  the  hibernating  puparia  had  ever  before 
been  at  that  season  of  the  year.  So  far  as  could  be  determined  even 
up  to  within  a  few  weeks  before  the  emergence  of  the  Hies  would 
naturally  take  place,  there  was  no  difference  in  the4  condition  of  the 
puparia  hibernated  in  different  kinds  of  soil  or  under  slightly  different 
environment . 

Beginning  quite  early  in  the  spring  and  continuing  through  a  con- 
siderable period,  flies  emerged  in  very  variable  proportions  from  the 
different  lots  of  puparia.  The  emergence  in  a  few  instances  was  well 
up  toward  100  per  cent.  In  others  it  was  much  lower,  and  in  a  few 
none  of  the  flies  completed  their  transformations.  The  reasons  for 
these  differences  were  not  obvious  in  every  instance,  but  it  was  ob- 
vious that  unless  conditions  are  practically  identical  with  those  which 
prevail  in  the  open,  the  flies  will  fail  to  issue  in  the  spring.  Moisture 
is  an  essential,  but  is  by  no  means  the  only  essential  to  success.  Nor 
can  failure  be  attributed  to  unduly  high  or  low  temperatures,  or-  un- 
natural and  abrupt  changes  in  the  temperature  during  the  period  of 
hibernation. 

The  average  percentage  of  emergence  from  all  of  the  different  lots 
of  pupae  has  not  been  as  yet  accurately  calculated,  but  it  was  far  in 
excess  of  any  that  was  secured  before,  and  three  colonies  which  were 
considered  to  be  satisfactorily  huge  and  strong  were  established  in 
different  parts  of  the  infested  area.  It  was  not  really  expected  that 
any  of  the  new  generation  would  be  recovered  from  the  held  during 
the  course  of  the  first  season,  and  it  was  therefore  considered  a  par- 
ticularly good  omen  when  a  few  were  recovered,  without  difficulty, 
and  under  conditions  which  indicated  that  dispersion  at  a  quite  rapid 
rate  had  accompanied  a  rapid  rate  of  increase.  The  species  has  not 
yet  been  placed  on  the  list  of  those  considered  as  thoroughly  estab- 
lished, since  it  is  not  certain  that  it  will  pass  through  the  complete 
seasonal  cycle  in  the  field,  but  it  is  confidently  expected  that  it  will 
live  through  successfully  and  that  it  will  be  recovered  in  1911  in  larger 
numbers.  If  these  expectations  are  realized  there  is  every  reason  to 
believe  that  it  will  become  a  parasite  of  consequence  within  the  next 
five  years. 


218         '      PARASITES  OF  GTPSY  AND  BROWN-TAIL  MOTHS. 

Curiously  enough,  among  the  imported  gipsy-moth  enemies  that 
which  most  nearly  resembles  Blepharipa  (if  the  practically  identical 
Crossocosmia  be  excepted)  in  the  part  which  it  will  probably  take  in 
the  control  of  the  gipsy  moth  is  Calosoma  sycophanta.  No  two  of  the 
imported  enemies  differ  more  radically  in  their  method  of  attack 
than  do  these,  the  extent  of  their  differences  being  fairly  well  exem- 
plified by  the  fact  that  the  gipsy  moth  eats  Blepharipa,  while  the 
Calosoma  eats  the  gipsy  moth,  which  is  literally  true. 

In  one  very  important  respect  they  are  similar  in  that  both  are 
able  to  exist  continuously  upon  the  gipsy  moth  without  being  forced 
to  have  recourse  to  any  other  insect  so  long  as  the  gipsy  moth  retains 
a  certain  degree  of  abundance.  Both  work  to  their  best  advantage 
and  multiply  most  rapidly  at  the  expense  of  the  moth  when  the  lat- 
ter is  superabundant. 

It  is  only  necessary  to  consider  the  powers  of  reproduction  (poten- 
tially several  {housandfold)  possessed  by  the  tachinid  to  see  what  an 
enormous  rate  of  increase  is  likely  to  prevail  in  localities  where  prac- 
tically complete  defoliation  occurs  without  becoming  so  complete  as 
to  bring  about  wholesale  destruction  of  the  gipsy  moth  through 
disease.  Under  such  circumstances  a  very  large  proportion  of  the 
eggs  deposited  upon  the  foliage  would  perforce  be  eaten,  as  compared 
with  the  proportion  eaten  were  the  caterpillars  present  in  small  num- 
bers. The  percentage  of  parasitism  would  remain  practically  the 
same  in  both  instances,  but  the  gross  number  of  parasites  completing 
their  transformations  would  be  tremendously  increased  with  a  result- 
ing increase  in  the  percentage  of  parasitism  the  following  generation, 
whenever  the  gipsy  moth  becomes  unduly  abundant.  In  like  manner 
the  Calosoma,  which  works  at  a  disadvantage  when  the  caterpillars  are 
scarce,  finds  the  conditions  resulting  through  superabundance  excep- 
tionally favorable  for  its  rapid  increase. 

Theoretically,  therefore,  Blepharipa  ought  to  act  as  an  agent  in 
the  reduction  in  the  prevailing  numbers  of  the  gipsy  moth  whenever 
it  exceeds  a  certain  degree  of  abundance,  and  this  is  the  role  which 
it  is  expected  to  play.  Theoretically,  Calosoma  will  play  practically 
the  same  role.  Together  their  activities  ought  to  result  in  the  break- 
ing up  of  dangerous  colonies  of  the  gipsy  moth,  and  thereby  render 
the  work  of  the  other  parasites  and  of  such  native  enemies  as  birds, 
predatory  bugs,  etc.,  doubly  effective. 

COMPSILURA  CONOINNATA  MEIG. 

Quite  a  good  many  of  the  parasites  of  the  gipsy  moth  attack  the 
brown-tail  moth  also,  but  there  is  only  one  among  them,  Compsilura 
concinnata  (fig.  41),  which  is  equally  important  as  a  parasite  of  both. 
The  remainder,  if  they  att  ack  both  hosts,  are  more  or  less  partial  to 
one  or  the  other. 


TACHIXID  PARASITES  OF  THE  GIPSY  MOTH. 


219 


In  its  method  of  attack  Compsilura  is  the  opposite  of  Blepharipa. 
It-,  egga  hatch  in  the  uterus  of  the  mother,  and  the  tin}'  magots  are 
deposited  beneath  tlie  skin  of  the  host  caterpillar  by  means  of  a 
sharp,  curved  "larvipositor,"  winch  is  situated  beneath  the  abdomen. 
They  usually  seek  the  alimentary  canal,  in  the  walls  of  which  they 
establish  themselves  during  the  first  stage  of  their  larval  existence. 

Growth  is  rapid,  and  in  the  summer  is  in  no  way  correlated  with 
the  growth  and  development  of  the  host.  About  two  weeks  are 
required  for  the  complete  development  of  the  maggot,  irrespective 
of  the  stage  of  the  host  at  the  time  of  attack,  and  at  the  end  of  that 
period  it  issues,  and  usually  drops  to  the  ground  for  pupation.  The 
puparia  from  maggots  which  issue  from  caterpillars  which  have  spun 
for  pupation  are  nol  infrequently  found  in  the  cocoons  in  the  case  of 

the  brown-tail  moth; 
and  even  in  the  case 
of  the  gipsj  moth, 
winch  does  not  spin 
cocoons  w  orthy  of  the 
name,  the  puparia  are 
often  found  immedi- 
ately associated  with 
the  host  remains. 

It  requires  a  sur- 
prisingly short  time 
for  the  females  to  at- 
tain full  sexual  matur- 
ity after  their  emer- 
gence, three  or  four 
days  apparently  being 
sufficient.  This,  with 
two  weeks  for  the 
growth  of  the  larva,  and  one  week,  or  perhaps  a  little  more,  for  the 
pupal  period,  makes  possible  a  generation  every  four  weeks  during 
the  warmer  months  of  the  \  ear. 

The  position  of  the  larva  in  the  alimentary  canal,  together  with 
certain  structural  characteristics,  consisting  of  minute  anal  hooks, 
w  hich  are  only  know  n  amongst  other  first-stage  tachinids  in  the  very 
similar  genus  Dexodes,  makes  possible  the  quite  accurate  determina- 
tion of  Compsilura  concinnata  from  its  first-stage  larva  alone,  and 
only  from  observations  which  have  been  made  upon  these  larva1  is 
it  possible  to  say  anything  definite  and  at  first  hand  concerning  its 
habits  of  hibernation.  Larvae,  which  are  almost  certainly  Compsi- 
lura concinnata,  have  been  occasionally  found  in  living  brown-tail 
moth  caterpillars  during  the  winter  months.  It  is  presumed  if  these 
larva1  were  able  to  mature  under  these  circumstances,  that  they 


Fir..  41.— Compsilura  concinnata:  Adult  female  and  details.  Much 
enlarged.  (Original.) 


220  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

would  have  been  reared  before  now  from  some  among  the  hundreds 
of  thousands  of  brown-tail  caterpillars  which  have  been  carried 
through  their  first  three  or  four  spring  stages  in  the  laboratory.  Xone 
having  been  reared  under  these  circumstances,  the  only  logical  con- 
clusion is  that  they  start  into  activity  so  early  and  develop  so  rapidly 
as  to  cause  the  death  of  the  host  before  they  are  sufficiently  advanced 
to  pupate  successfully.  This  is  not  necessarily  the  true  explanation 
of  the  failure  to  rear  the  species  from  hibernating  brown-tail  cater- 
pillars fed  in  confinement,  but  it  appears  to  be  the  best. 

Ordinarily  in  the  summer  the  larvae  do  not  pass  over  into  the  pupa 
of  the  host,  but  occasionally  they  do  so.  In  the  late  summer  and 
fall,  when  the  host  caterpillar  is  of  a  species  which  hibernates  as  a 
pupa,  the  parasite  appears  to  be  aware  of  that  fact  in  some  subtle 
manner,  and  likewise  prepares  for  hibernation.  Its  larvae  (or  what 
are  without  much  doubt  its  larvae)  have  several  times  been  found  in 
hibernating  pupae  of  several  species.  The  adult  has  never  yet  been 
reared  from  pupae  under  these  circumstances,  and  the  record  is  on 
that  account  open  to  some  question. 

The  larger  part  of  the  Compsilura  which  were  imported  from  1906  to 
1908,  inclusive,  issued  from  puparia  (PI.  XX,  fig.  1)  found  free  in  the 
boxes  of  brown-tail  caterpillars  from  abroad.  A  companion  species, 
Dexodes  nigripes,  which  is  indistinguishable  from  Compsilura  in  any 
of  its  preparatory  stages,  has  also  been  reared  under  exactly  similar 
circumstances,  but  curiously  enough,  if  Compsilura  was  common  in 
material  from  the  same  locality,  Dexodes  was  apt  to  be  rare,  or  vice 
versa.  Some  few  were  reared  from  gipsy-moth  importations  during 
this  same  period,  but  not  in  anything  like  the  numbers  which  were 
secured  from  the  brown-tail  moth  material,  and  it  was  not  considered 
as  of  particular  importance  as  a  gipsy-moth  parasite  until  1909, 
when  it  was  found  to  be  very  common  among  the  tachinid  parasites 
secured  from  shipments  of  gipsy-moth  caterpillars  from  southern 
France. 

The  first  colonies  of  Compsilura  were  planted  in  various  localities 
within  the  gipsy-moth  infested  area  in  1906,  and  in  1907,  according 
to  the  records  of  the  laboratory,  a  single  fly  was  reared  from  gipsy- 
moth  caterpillars  collected  in  the  immediate  vicinity  of  one  of  these 
colonies.  There  is  some  reason  to  doubt  the  truth  of  this  record, 
since  every  attempt  at  recovery  made  in  1908  failed. 

In  1907  a  much  larger  colony  than  any  ever  liberated  before  was 
located  in  the  town  of  Saugus,  in  the  near  vicinity  of  one  of  those  of 
the  previous  season.  In  1908  none  was  colonized.  In  1909  several 
very  Large  and  satisfactory  colonies  were  planted  in  several  places 
within  the  infested  area,  and  for  the  first  time  it  was  felt  that  the 
species  had  been  given  a  fair  opportunity  to  prove  its  effectiveness 
as  an  enemy  of  the  gipsy  moth  and  brown-tail  moth  in  America. 


TACHTXID  PARASITES  OF  THE  GIPSY  MOTH. 


221 


Hardly  was  the  final  establishment  of  what  was  for  a  few  days 
considered  to  be  the  first  satisfactory  colony  of  Compsilura  concin- 
nata  accomplished  than  the  necessity  for  the  expenditure  of  further 
labor  on  its  account  was  obviated  by  the  discovery  that  it  could  be 
recovered  from  the  field  in  small  but  at  the  same  time  in  very  satis- 
factory numbers.  Only  an  insignificant  number  was  reared  from  the 
collections  of  gipsy-moth  caterpillars  made  in  1 !»()!).  but  later  in  the 
fall  of  that  year  field  men  who  were  scouting  for  evidences  of  the 
spread  of  Calosoma  and  searching  under  burlap  bands  for  its  molted 
Larva]  >kin>  began  to  bring  into  the  laboratory  bona  fide  puparia  of 
Compsilura  found  under  the  same  circumstances.  It  was  thus  pos- 
sible to  delimit  its  range  with  some  accuracy,  and  it  was  found  to 
extend  over  a  considerable  territory,  with  the  1906-7  colony  in 
Saugus  much  nearer  to  its  center  than  any  other  more  recently 
located  colony.  (See  fig.  42.)  There  could  he  no  doubt  that  the 
species  was  well  established  and  spreading  and  multiplying  at  a  rapid 
rate. 

The  results  of  the  season  of  1910  were  awaited  with  very  great 
interest,  in  expectation  that  they  would  confirm  those  of  the  year 
before.  That  these  were  confirmed,  and  most  conclusively  and 
satisfactorily,  is  evidenced  by  the  results  of  the  rearing  work  as 
summarized  in  Tables  IV  and  Y  (pp.  111.  112),  which  give  the 
results  of  rearing  work  for  thai  year.  The  i<>t;il  number  of  the 
parasites  reared  or  otherwise  recovered  from  the  field  as  indicated 
by  these  tables  is  very  far  Bhorl  of  tin4  total  secured. 

Compsilura  concinttata  is  recorded  as  a  parasite  of  a  large  number 
of  hosts  in  Europe,  and  will  doubtless  be  found  to  attack  an  equally 
large  number  in  America  when  it  shall  have  become  thoroughly 
established  and  abundant  over  a  wide  territory.  Already  some  half 
dozen  native  hosts  are  known,  and  it  would  easily  be  possible  to 
double  or  treble  this  list  in  the  course  of  another  season's  work, 
should  it  be  conducted  with  that  end  in  view. 

Few  subjects  for  speculation  are  so  overcrowded  with  possibilities 
as  that  of  the  effect  which  the  importation  of  new  parasites  having 
a  wide  range  of  hosts  will  have  upon  native  parasites  and  their  hosts. 
The  increasing  abundance  of  Compsilura  offers  a  most  excellent 
opportunity  to  answer  numerous  questions  which  naturally  arise 
when  this  subject  is  considered,  and  it  is  hoped  that  it  may  be  made 
the  most  of.  Already  several  highly  significant  observations  have 
been  made. 

One  of  the  most  interesting  of  these  resulted  from  a  series  of  col- 
lections of  tussock-moth  caterpillars  made  by  Mr.  Wooldridge  in 
the  summer  of  1910  for  the  purpose  of  determining  the  prevalence 
of  parasitism  in  various  localities  and  under  slightly  different  condi- 
tions.   All  of  these  collections  were  of  necessity  made  under  urban 


222 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


conditions,  since  the  tussock  moth  is  rare  in  the  country  in  eastern 
Massachusetts,  and  while  it  was  expected  that  Compsilura  would 
eventually  be  recovered  as  a  parasite  of  this  host,  it  was  hardly 
expected  that  it  would  become  of  importance  as  a  parasite  so  soon 
as  1010,  or,  for  that  matter,  that  it  would  become  of  importance  as  a 
parasite  in  cities  at  any  time. 


TOWA/S  WHERE  COMPS/LC/RA  COA/C/A/A/ATA 

was  foc/a/o  paras/ r/c  o/v  broia/a/-ta/l  /a/  /sos 


V/XA  TOWNS  WHERE  COMP- 
X////*S/LURA  COA/C/A/A/ATA  WAS 


TOWA/S  WHERE  COMPS/LURA 
COA/C/A/A/ATA  WAS  EOOA/D  PARA 


FOUA/D  PARAS/T/C  O/V  BROWA/-TA/L  //V 
 /3/Q.  


S/T/C  OA/P/ER/S  /A/  FALL  OF/9/0. 


Y\q,  42.— Map  showing  distribution  of  Compsilura  concinnata  in  Massachusetts.  (Original.) 

The  only  one  of  the  localities  chosen  for  the  tussock-moth  col- 
lections which  was  within  the  limits  of  Compsilura's  distribution 
so  far  as  known  when  the  work  was  instituted  was  in  the  city  of 
Lynn,  Mass.,  and  from  this  a  total  of  110  caterpillars  was  collected 
on  July  18,  1910.  On  July  29  the  tray  in  which  they  were  contained 
was  carefully  examined.    Thirteen  of  the  tussock-moth  caterpillars 


TACHINID  PARASITES  OF  THE  GIPSY  MOTH. 


223 


had  pupated  and  remained  alive.  The  remainder  had  died,  principally 
as  the  result  of  parasitism. 

In  all  96  tachinid  puparia  and  1  cocoon  of  Meteorus  were  found. 
Of  these  puparia  95  were  Compsilura  concinnata  and  the  other 
apparently  Tachi na  India.  The  Meteorus,  incidentally,  proved  to 
be  of  the  introduced  species,  \I<  f<  <>/■>/«  msicolor. 

Parasitism  by  native  tachinids  was  probably  considerably  higher 
than  would  be  indicated  by  the  fact  that  only  a  single  puparium 
was  secured  as  against  9o  of  the  imported  species,  but  because  the 
latter  completes  its  larval  development  much  more  rapidly  than 
does  Tachina  mella,  it  would  almost  certainly  be  the  victor  in  case 
of  a  conflict. 

Later  collections  of  tussock-moth  caterpillars  made  for  the  express 
purpose  of  determining  tin'  limits  to  the  distribution  of  Compsilura 
resulted  in  its  discovery  throughout  practically  all  of  greater  Boston, 
and  it  may  he  that  it  will  have  some  effect  in  reducing  the  importance 
of  this  insect  as  a  pest  in  that  city  and  its  Buburbs.  With  the  end 
of  experimenting  further  along  this  line  the  puparia  secured  from 

the  Lynn  collection,  together  with  several  hundred  more  From  gipsy- 
moth  caterpillars,  were  sent  t«>  Washington,  where  they  were  liberated 
upon  the  grounds  of  t he  1  department  of  Agriculture,  where  the  tussock 
mot  h  18  periodically  a  pest . 

Another  indication  of  good  which  may  possibly  result   from  the 

introduction  of  this  tachinid  resulted  From  an  investigation ,  begun  in 
September,  1910,  by  Mr.  J.  D.  Tot  hill,  into  the  parasites  of  t  be  imported 
cabbage  butterfly  {[Pieris]  Pontic  rap&  L>.  He  found  that  in  locali- 
ties where  Compsilura  was  known  to  be  common  the  summer  before, 
it  was  actually  abundant  as  a  parasite  of  this  pest .  and  as  high  as  40 
per  cent  had  heen  attacked  in  some  instances. 

There  is  no  native  tachinid  known  to  have  quite  the  same  habits 
as  Compsilura,  neither  is  there  any  with  quite  so  varied  a  list  of 
hosts.  Both  the  cabbage  butterfly  and  the  tussock  moth  are  com- 
monly considered  as  pests,  the  one  generally  and  the  other  in  cities, 
and  both  can  probably  sustain  additional  parasitism  without  much 
difficulty.  But  in  the  case  of  the  other  native  insects  liable  to  attack 
by  the  imported  parasite,  and  already  thoroughly  well  controlled  by 
various  agencies,  of  which  parasitism  is  one,  the  outcome  of  the 
struggle  which  is  likely  to  ensue  is  probably  going  to  be  different. 
In  the  case  of  such  an  one  it  is  reasonably  safe  to  predict  that  one  of 
two  things  will  happen.  Either  the  prevailing  abundance4  of  the 
Lost  will  he  reduced  through  the  introduction  of  a  new  factor  into 
its  natural  control,  or  the  host  will  maintain  its  present  relative 
abundance,  and  its  parasites  will  suffer  directly  in  the  struggle  into 
which  they  will  he  forced  by  the  advent  of  the  tachinid. 


224  PARASITES  OF  GIPSY  AND  BROWX-TAIL  MOTHS. 


It  is  yet  too  soon  to  begin  to  speculate  upon  what  the  actual  out- 
come in  specific  instances  will  be.  An  investigation  of  the  parasites 
of  the  fall  webworm  was  undertaken  in  the  fall  of  1910  on  the  suppo- 
sition that  Compsilura  would  find  it  an  acceptable  host,  but  although 
it  is  freely  attacked  when  outside  of  its  web  in  rearing  cages  in  the 
laboratory,  it  was  not  at  all  commonly  attacked  in  the  open,  as  will 
be  seen  by  reference  to  the  brief  summary  of  the  results  of  the  work 
in  the  concluding  pages  of  this  bulletin. 

There  has  never  been  a  good  opportunity  to  study  the  parasites 
of  the  Tachinidse,  owing  to  the  fact  that  some  of  the  species  pupate 
upon  or  beneath  the  surface  of  the  soil,  and  are  therefore  difficult  to 
find  in  sufficient  quantities  to  make  a  comprehensive  study  possible. 
So  abundant  was  Compsilura,  however,  as  to  make  it  possible  to 
collect  its  puparia  in  considerable  abundance  and  with  comparatively 
little  trouble  at  the  base  of  trees  upon  which  the  gipsy-moth  cater- 
pillars were  common,  and  accordingly  a  number  was  so  collected  in 
the  late  summer  of  1910.  Not  enough  attention  was  given  to  the 
work  to  make  the  results  as  definite  as  is  desired,  but  these  were 
sufficient  to  indicate  that  secondary  parasitism  was  undoubtedly  of 
very  common  occurrence,  and  that  it  might  be  a  factor  of  some  con- 
sequence in  limiting  the  effectiveness  of  the  parasite.  No  less  than 
six  species  of  secondaries  were  reared,  including  Monodontomerus 
sereus,  which  was  common,  Dibrachys,  another  small  chalcidid,  a 
species  of  Chalcis,  a  proctotrypid,  and  a  Phygadeuon.  It  is  hoped 
that  circumstances  will  permit  of  a  more  thorough  study  of  this 
subject  in  1911,  and  should  the  parasite  show  an  increase  propor- 
tionate to  that  which  was  indicated  by  its  abundance  in  1910  over 
that  of  1909,  the  project  should  be  very  easy  of  accomplishment. 

It  is  fortunate  that,  under  the  present  circumstances,  with  the 
gipsy  moth  and  the  brown-tail  moth  both  exceedingly  abundant  and 
uncontrolled,  there  should  be  at  least  one  parasite  which  was  equally 
drawn  toward  both.  It  is  easily  possible  that  the  first  individuals 
which  are  reared  upon  the  brown-tail  moth  as  a  host  may  attack  the 
full-fed  caterpillars  for  a  partial  second  generation  the  same  season, 
and  then,  together  with  the  bulk  of  the  brood  coining  from  this  host, 
turn  their  undivided  attention  to  the  gips}r-moth  caterpillars.  In  a 
similar  manner  the  first  individuals  to  go  through  their  transforma- 
tions upon  the  gipsy  moth,  together  with  the  partial  second  genera- 
tion upon  the  brown-tail  moth,  may  attack  the  less  advanced  gipsy- 
moth  caterpillars  for  a  partial  third  brood  before  the  necessity  for 
an  alternate  host  becomes  apparent. 

There  is  thus  possible  uninterrupted  increase  for  two  complete  gen- 
erations  at  least,  and  probably  for  a  partial  third,  but  unfortunately 
the  necessity  for  an  alternate  host ,  though  delayed  until  no  more  than 
one  such  host  is  necessary  in  order  that  the  seasonal  cycle  may  be 


TACHINID  PARASITES  OF  THE  GIPSY  MOTH. 


225 


rounded  out,  is  not  done  away  with.  Unless  the  parasite  hibernates 
in  the  brown-tail  caterpillars  such  a  hosl  must  be  found  among  the 
native  Lepidoptera,  and  while  the  number  of  species  available  prob- 
ably runs  into  the  hundreds,  the}"  are,  with  few  exceptions,  already 
controlled  by  their  native  parasites.  Compsilura,  if  it  continues  to 
increase,  will  have  to  overcome  these  parasites  in  the  competitive 
struggle  for  possession,  and,  as  already  stated,  the  outcome  of  this 
struggle  is  awaited  with  interest.  Upon  it  will  very  Largely  depend 
the  effectiveness  of  Compsilura  as  a  parasite  of  the  gipsy  moth  and 
the  brown-tail  moth  in  America. 

TACHINA  LABVABUM  L. 

This  rather  important  parasite  of  the  gipsy  moth  (fig.  43),  and  to  a 
more  limited  extent  of  the  brown-tail  moth  in  Europe,  is  so  simi- 
lar to  the  Ameri- 
can Tachina  nulla 
Walk,  as  to  make 
the  separation  of 
the  two  by  struc- 
tural characters 
alone  difficult  at 
best ,  and  in  some 
instances  impossi- 
ble. It  is  similarly 
closely  allied  to 
T a  ch  ina  japonica 
Tm\\  iis.,  and  the 
three  species  or 
races  appear  to  oc- 
cupy about  the 
same  position  in 
the  natural  order 
of  things  in  the  several  countries  which  they  inhabit.  The  European 
and  the  American  are  both  quite  catholic  in  their  host  relations,  and 
while  the  same  can  not  be  said  of  the  Japanese  in  the  present  state 
of  our  knowledge4,  it  will  doubtless  be  found  true  when  this  knowledge 
shall  be  m< >re  extensive. 

From  an  economic  standpoint  Tachina  nulla  and  Tachina  larvarum 
are  distinct  enough  specifically,  if  we  are  to  consider  their  parasitism 
from  an  economic  aspect,  since  the  one  is  habitually  and  commonly  a 
parasite  of  the  gipsy  moth,  while  the  other  is  not.  It  would  appear  that 
Tachina  mella  attacks  the  gipsy  moth  quite  as  freely  in  America  as 
Tachina  larvarum  does  in  Europe,  but,  as  has  already  been  mentioned, 
the  attack  is  not  successful  from  either  the  economist's  or  the  parasite's 
point  of  view. 

95677°— Bull.  01—11  15 


Fig.  43. —  Tachina  lartarum:  Adult  female  and  head  in  profile.  Enlarged. 
(Original.) 


226  PAKASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

This  is  one  of  the  less  striking  of  several  examples  of  a  species  which 
differs  from  another  in  biological  rather  than  in  structural  charac- 
teristics. Others  are  to  be  found  in  the  European  race  of  Tricho- 
gramma,  in  the  Japanese  Apanteles  parasitic  upon  Euproctis  con- 
spcrsa,  which  so  resembles  the  brown-tail  Apanteles  of  Europe,  or  in 
Parexorista  chelonise,  examples  which  will  be  again  referred  to  on 
subsequent  pages. 

The  large,  flattened,  and  conspicuous  eggs  characteristic  of  Tachina 
and  its  allies  are  the  most,  and  in  fact  the  only  familiar  type  of  tachinid 
eggs,  and  they  are  deposited  before  embryological  development  has 
taken  place  in  at  least  a  part  of  the  instances  which  have  come  under 
direct  observation.  The  larva  issues  through  an  irregular  hole  in  one 
end,  and  immediately  forces  an  entrance  through  the  skin  of  its  host. 
The  life  cycle  is  longer  than  in  the  case  of  Compsilura,  but  just  how 
much  longer  is  not  known.  Sometimes  the  larva  is  carried  over  into 
the  pupa  of  its  host,  but  not  very  often.  Very  frequently  it  kills  the 
host  after  it  has  prepared  for  pupation.  Nearly  always  it  leaves  the 
host  remains  before  pupating,  on  its  own  account,  but  occasionally 
pup  aria  within  the  caterpillar  skin  or  pupal  shell  are  found. 

The  puparium  (PL  XX,  fig.  2),  unfortunately,  is  practically  insepa- 
rable from  that  of  Tricholyga  grandis  or  Parasetigena  segregata  in  its 
structural  details,  so  that  it  is  necessary  to  rear  the  fry  before  the  spe- 
cies can  be  determined. 

As  a  parasite  of  the  gipsy  moth,  Tachina  larvarum  may  and  some- 
times does  take  preeminent  rank.  Caterpillars  from  Holland  have 
been  received  from  which  more  pup  aria  were  secured  than  there  were 
hosts,  and  the  same  has  occurred  on  at  least  one  other  occasion  in  the 
instance  of  a  box  of  caterpillars  from  Italy.  When  Tricholyga  grandis 
is  common,  Tachina  larvarum  is  rare,  or  at  least  has  been  rare  in  each 
instance  in  which  the  two  species  have  been  specifically  determined 
as  they  issued  from  the  imported  material.  It  has  also  been  entirely 
absent  from  some  lots  of  caterpillars  which  did  not  produce  Tricholyga. 

It  was  about  the  first,  if  not  the  very  first,  parasite  to  be  received 
alive  in  the  course  of  the  parasite-introduction  work,  and  mention 
will  be  found  in  Mr.  Kirkland's  first  report  as  superintendent  of  moth 
work,  of  its  having  been  reared  from  Italian  material  in  1905.  It  was 
not  secured  in  sufficient  abundance  to  make  colonization  possible 
until  1906,  but  in  that  year  quite  a  number  of  small  colonies  was 
planted  in  various  localities  in  the  infested  territory.  In  1907  it  was 
received,  but  in  not  such  large  numbers,  and  still  smaller  numbers 
were  secured  and  colonized  in  1908.  In  1909,  for  the  first  time,  really 
satisfactory  colonies  were  planted,  and  one  of  these  colonies  was 
strengthened  by  the  liberation  of  more  individuals  in  1910. 

So  far  as  it  has  been  possible  to  determine,  no  results  followed  these 
several  attempts  at  colonization.    Of  all  of  the  tachinids  liberated  in 


TACHIXID  PARASITES  OF  THE  GIPSY  MOTH. 


227 


1906,  this  was  colonized  the  most  satisfactorily,  or  so  it  is  believed 
(having  been  confused  with  Tricholyga  grandis  it  is  impossible  to  state 
definitely  which  of  the  two  was  the  more  abundantly  reared  and 
liberated  that  year),  and  it  ought  to  have  been  recovered  by  1910  if 
it  is  ever  to  be  recovered  as  a  result  of  early  colonizations.  That  it 
has  not  been  recovered  as  a  result  of  the  1909  colonization  work  is  not 
at  all  surprising,  because  there  is  every  prospect  of  two  or  three  years 
elapsing  between  the  liberation  and  the  recovery  of  any  species,  and 
more  particularly  of  those  which,  like  Tachina  and  many  others  of  the 
tachinid  parasites  of  both  the  gipsy  moth  and  the  brown-tail  moth, 
are  not  received  from  abroad  until  after  the  season  is  so  far  advanced 
as  to  make  immediate  reproduction  upon  either  of  the  hosts  mentioned 
impossible. 

It  is  unfortunately  true  that  it  would  be  impossible  to  distinguish 
it  from  Tachina  meUa,  should  it  be  reared,  since  T.  meUa  is  occasionally 
reared  a^  a  parasite  of  the  gipsy  moth  or  the  brown-tail  moth,  but  it 
is  still  more  unfortunate  that  no  adults  of  any  Bpecies  which  could  by 
any  possibility  be  referred  to  either  were  reared  in  1910  from  the 
gipsy  moth. 

In  1910  Messrs.  Thompson  and  Tot  lull  conducted  an  experiment  to 
determine  whether  T.  nulla  and  '/'.  larvarwn  would  hybridize.  The 
result^  were  negative  and  not  of  sufficient  strength  to  be  at  all  deci- 
sive. If  it  could  be  proved  that  hybridization  took  place  freely,  the 
fact  in  itself  would  probably  be  sndicient  to  render  the  Knropean 
species  of  no  account  as  an  enemy  of  the  gipsy  moth  in  America. 
Interbreeding  with  a  vastly  superior  number  of  another  race,  the 
principal  and  only  economically  important  distinguishing  characteris- 
tic of  which  was  inability  to  breed  upon  a  certain  host,  would  un- 
doubtedly result  in  the  linking  of  the  racial  characteristic,  and  T. 
larvarum  as  a  race  would  almost  immediately  cease  to  exist.  This  is 
the  more  probable  in  the  light  of  the  experiences,  yet  to  be  related, 
which  attended  the  attempted  introduction  of  the  brown-tail  parasite 
Pan  xorista  chclonise. 

On  this  account,  and  on  no  other.  Tachina  larvarum  has  been  ten- 
tatively eliminated  from  the  list  of  promising  parasites  of  the  brown- 
tail  moth  and  the  gipsy  moth.  It  may  not  establish  itself  here  in 
America,  and  under  the  peculiar  circumstances,  proof  to  the  con- 
trary being  lacking,  its  possible  hybridization  may  make  further 
attempts  to  import  it  useless. 

TACHINA  JAPONICA  TOWNS. 

Pretty  nearly  all  that  has  been  said  of  Tachina  larvarum  may  be 
said  with  equal  truth  of  Tachina  iaponica.  in  so  far  as  its  value  in 
America  is  concerned.  It  may  possibly  be  that  it  is  sufficiently 
distinct  as  a  species  to  make  possible  its  successful  establishment, 


228 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


even  presuming  that  T.  larvarum  should  not  be  established,  but  the 
chances  are  not  particularly  in  favor  of  such  an  outcome.  It  has 
not  been  so  long  nor  so  satisfactorily  colonized,  and  there  is  yet  a 
chance  that  it  will  be  recovered  as  a  result  of  the  colonies  which  have 
been  planted,  or  which  are  likely  to  be  planted  in  the  future.  Xo 
especial  attempt  will  be  made  to  test  its  ability  to  exist  as  a  race  apart 
from  T.  mella,  but  it  is  expected  that  its  puparia  will  be  imported  in 
some  numbers  in  1911  or  in  1912,  in  connection  with  work  involving 
the  importation  of  other  Japanese  parasites. 

TRICHOLYGA   GRANDIS  ZETT. 

Although  generic-ally  distinct  from  Tachina,  according  to  the  at 
present  accepted  and  as  is  increasingly  evident  artificial  classification 
of  the  Tachinida?,  Tricholyga  grandis  is  so  similar  to  Tachina  mella 
and  T.  larvarum  as  sometimes  to  be  separated  with  difficulty  from 
those  species.  In  Europe  Tachina  and  Tricholyga  attack  the  gipsy 
moth  with  nearly  equal  freedom,  but  relatively  a  very  few  Tricholyga 
have  been  reared  from  the  brown-tail  moth.  The  fact  that  Tachina 
and  Tricholyga  do  not  usually  occur  in  the  same  locality  the  same 
year  has  already  been  the  subject  of  comment.  If  may  be  that  a 
careful  review  of  the  rearing  records  of  the  two  will  show  that 
Tricholyga  is  increasingly  important  as  a  parasite  in  the  more  south- 
erly localities,  but  such  review  has  not  been  made  with  this  point  in 
view. 

It  was  not  until  1909  that  it  was  definitely  separated  from  Tachina 
in  the  records  of  the  rearing  and  liberation  of  the  tachinid  parasites, 
and  up  to  1908  the  two  species  were  so  inextricably  mixed  as  to  make 
it  very  difficult  to  state  with  any  approach  to  accuracy  the  relative 
proportions  of  the  two  among  the  number  colonized.  There  was 
only  a  single  specimen  of  Tricholyga  among  the  several  Tachina  which 
were  preserved  for  museum  specimens  from  among  those  imported 
in  1906  and  1907,  and  on  this  account  it  is  probable  that  Tachina  was 
in  the  considerable  majority. 

In  habits  Tricholyga  differs  from  Tachina  in  only  a  single  con- 
spicuous respect.  It  deposits  the  same  sort  of  eggs,  similarly  placed ; 
it  s  larvae  appear  to  have  the  same  feeding  habits,  and  about  the  same 
length  of  life  cycle;  but  unlike  Tachina  it  seems  habitually  rather 
t  han  occasionally  to  pupate  within  the  caterpillar  skin  or  pupal  shell 
of  its  victim.  On  this  account  some  of  its  puparia  have  been  diffi- 
cult to  find  in  the  boxes  of  imported  caterpillars,  and  it  has  been 
found  advisable  when  they  are  present  at  all,  to  keep  the  dead  cater- 
pillars inclosed  until  such  flies  as  are  present  have  emerged. 

Like  Tachina,  it  probably  hibernates  in  the  puparium,  but  neither 
of  the  two  lias  ever  attempted  to  hibernate  when  reared  from  im- 
ported  European  gipsy-moth  caterpillars.    The  introduction  and 


TACHIXID  PARASITES  OF  THE  GIPSY  MOTH. 


229 


establishment  of  Tricholyga  will  depend  upon  the  existence  of  an 
alternate  host,  and  its  effectiveness  as  a  parasite  upon  its  ability  to 
make  a  place  for  itself  in  the  established  American  fauna.  Several 
attempts  to  secure  its  reproduction  in  the  laboratory  on  other  hosts 
than  the  gipsy  moth  have  been  measurably  successful,  and  there  is 
good  reason  to  believe  that  it  will  find  conditions  suitable  to  its  con- 
tinued existence  here. 

Notwithstanding  its  similarity  to  Tachina  it  appears  to  be  a  per- 
fectly good  and  distinct  species,  and  since  it  is  not  known  to  be 
represented  by  any  very  close  ally  in  America,  the  objections  which 
have  been  raised  against  the  probable  establishment  of  Tachina  do 
not  apply. 

It  is  unfortunately  impossible  to  say  more  concerning  the  likeli- 
hood of  its  becoming  established  here,  since  there  is  much  doubt  con- 
cerning its  colonization.  If.  as  is  possible,  it  formed  the  bulk  of  the 
so-called  Tachina  liberated  in  1906  and  1907,  it  ought  to  have  been 
recovered  before  now:  if,  on  the  contrary,  it  was  sparingly  present 
among  the  tachinids  reared  and  liberated  during  those  years,  there  is 
no  reason  to  expect  its  recovery  before  1911.  and  perhaps  not  until 
1912,  as  the  direct  result  of  the  huge  colonies  which  were  liberated 
in  WHY.),  and  which  would  represent  the  first  satisfactory  colonization 
of  t  he  species  in  America. 

In  the  popular  bulletin  issued  in  the  Bpring  of  1910,  through  the 
office  of  the  State  forester  of  Massachusetts,  it  was  stated  that  in  the 
fall  of  1909  it  had  already  been  recovered  upon  several  occasions  as  a 
parasite  of  the  gipsy  moth,  and  under  such  circumstances  as  to  make 
it  possible  that  it  was  already  established  and  dispersing  rapidly. 
This  statement  was  in  part  at  least  based  upon  erroneous  identification, 
but  at  the  present  date  it  is  expected  that  1911,  or  at  the  latest  1912, 
will  see  its  recovery  under  bona  fide  circumstances  as  an  established 
and  promising  parasite  of  the  gipsy  moth. 

PARASETIGEXA    SE(JKE(1  ATA  ROM). 

A  third  species  of  the  group  which  includes  Tachina  and  Tricholyga, 
and  which  deposits  similar  large,  flattened  eggs,  is  to  be  found  in 
Paiasetigena  segregate^  which  occurs  throughout  Europe  in  very 
variable  abundance  as  a  parasite  of  the  gipsy  moth,  but  not  of  the 
brown-tail  moth.  Tt  is  the  onespecies  of  gipsy-moth  parasite  which 
appeals  to  be  more  common  toward  the  northern  limits  of  the  range 
of  this  particular  host,  a  fact  which  may  be  explained  in  part  by  the 
fact  that  it  is  a  common  parasite  of  the  nun  moth  (Liparis  monacha  L.) 
as  well.  Tt  differs  from  either  Tachina  or  Tricholyga  in  that  it  has  but 
a  single  generation  a  year.  It  hibernates  in  the  puparium,  and  the 
flies  issue  coincident  ly  with,  or  perhaps  if  anything  a  little  in 
advance  of,  those  of  Blepharipa  in  the  spring. 


230 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Consequently  it  possesses  the  material  advantage  of  being  in- 
dependent of  an  alternate  host,  and  theoretically  there  is  nothing 
to  prevent  its  rapid  increase  whenever  conditions  favor  the  increase 
of  the  gipsy  moth.  The  most  that  can  be  said  against  it  is  its  in- 
ability  to  effect  the  control  of  its  other  and  apparently  more  favored 
European  host,  the  nun  moth,  which  to  a  greater  extent  than  the 
gipsy  moth  is  a  pest  in  the  forests  of  northern  and  central  Europe. 
Perhaps  it  may  find  conditions  in  America  more  favorable  than 
in  Europe,  and  thereby  be  able  to  do  more  toward  effecting  the  con- 
trol of  its  host  here  than  abroad. 

So  far  as  known  its  larval  habits  agree  very  exactly  with  those  of 
Tachina  in  all  of  their  essential  particulars.  It  leaves  the  host 
caterpillar  before  pupation,  and  only  upon  rare  occasions  is  carried 
over  into  the  pupa. 

The  first  specimens  which  were  reared  in  connection  with  the 
work  of  parasite  introduction  were  found  mingled  with  those  of 
Blepharipa,  which  issued  from  hibernated  puparia  in  the  spring  of 
1908.  There  were  only  a  very  few  of  them,  but  there  were  enough 
to  make  it  possible  for  Mr.  Townsend  to  determine  the  salient  features 
in  its  life  history  and  to  create  a  desire  to  secure  more  for  colonization 
purposes. 

Kelatively  very  few  puparia  were  secured  in  importations  of  1908, 
and  it  remained  for  those  of  1909  to  produce  the  number  which  was 
necessary  to  make  a  satisfactory  colony  of  the  species  possible.  Its 
puparia  being  indistinguishable  from  those  of  Tachina  and  Tricholyga, 
it  was  necessary  to  await  the  emergence  of  those  species  before 
attempting  to  count  upon  Parasetigena,  but  after  the  others  of  the 
Tachina  group  had  ceased  to  issue,  it  was  found  that  a  very  satisfactory 
number  of  unhatched  and  healthy  puparia  remained.  This  number 
was  subsequently  increased  by  the  importation  of  several  hundred 
which  had  been  reared  from  the  nun  moth,  and  which  subsequently 
proved  to  be  specifically  identical  with,  or  at  least  indistinguishable 
from  those  from  the  gipsy  moth. 

For  the  most  part  these  puparia  successfully  hibernated,  and  in 
excess  of  1,000  of  the  flies  were  reared  in  the  spring  and  colonized 
in  one  locality  where  there  was  every  opportunity  for  them  to  mul- 
tiply to  the  limit  of  their  powers  upon  the  gipsy  moth.  An  attempt 
to  recover  the  species  in  the  locality  later  in  the  season  failed,  but 
since  it  was  not  expected  that  it  would  be  recovered  so  soon  the 
disa  ppointment  was  not  very  keen.  It  would  undoubtedly  be  more 
encouraging  from  a  practical  standpoint  if  it  were  positively  known 
that  the  species  was  reproducing  freely,  but  the  failure  to  recover  it 
is  in  no  w&y  so  significant  as  would  have  been  the  failure  in  the  case 
of  Blepharipa. 


TACHINID  PARAS  IT  KS  OF  THE  GIPSY  MOTH. 


231 


Blepharipa,  which  was  colonized  in  the  same  locality  and  under 
the  same  circumstances  and  subsequently  recovered,  does  not •  leave 
its  host  until  after  the  latter  has  pupated,  and  since  the  collection 
of  pupa*  is  very  much  less  difficult  than  the  collection  of  caterpillars, 
its  recovery  was  that  much  more  easy  and  certain.  Although 
upward  of  a  dozen  Blepharipa  were  secured  from  collections  made 
in  this  colony,  all  of  them  were  from  pupae  and  none  from  the  cater- 
pillars which  had  to  be  depended  upon  for  Parasetigena. 

A  determined  effort  will  be  made  to  recover  both  species  in  1911, 
and  the  results  of  the  season  are  anticipated  with  much  interest. 

C  ARC  ELLA   ONAVA  MEIG. 

This  is  probably  the  least  understood  of  the  tachinid  parasites  of 
the  gipsy  moth.  It  appears  t<>  he  not  at  all  well  distributed  through- 
out Europe  and  has  never  appeared  in  sufficient  abundance1  to  give 
it  rank  as  among  the  important  parasites  except  in  the  material 
from  southern  France.  From  that  region  it  has  been  secured  in 
sullicieut  numbers  to  make  its  colonization  possible  on  a  scale  that 
is  quite  as  satisfactory  as  the  colonization  of  Tricholyga,  or,  for  that 
matter, of  Compsilura  until  alter  Oompsilura  was  found  to  be  estab- 
lished. 

It  was  received  in  gipsy-moth  caterpillar  importations  as  early  as 
19(H).  but  in  very  small  numbers  in  that  year,  and  in  --till  smaller 
numbers  in  1907  and  190X.  In  i<)09  the  very  large  and  until  then 
unprecedented  importations  from  the  Hydres  region  produced  several 
thousands  of  (lies,. and  more  were  received  in  1910.  which  went  to 
strengthen  colonies  of  the  previous  year.  Curiously  enough,  in  1910 
it  was  almost  the  only  tachinid  parasite  secured  from  this  region, 
on  account  of  which  the  gross  number  colonized  is  in  excess  of  any 
other  species.  Like  Tachina,  Tricholyga.  and  Compsilura,  it  is 
practically  certain  that  an  alternate  host  will  be  a  requisite  if  it  is  to 
complete  its  seasonal  cycle  in  America.  If  this  disadvantage  can 
be  overcome,  there  is  every  reason  to  expect  its  recovery  in  1911  or 
1912.  That  it  was  not  recovered  in  1910,  in  spite  of  the  fact  that 
some  10,000  caterpillars  of  the  gipsy  moth  were  collected  in  the 
immediate  vicinity  of  the  most  satisfactorily  liberated  colony  of  the 
summer  before,  entirely  loses  its  significance  when  it  is  taken  into 
account  that  neither  was  Compsilura  recovered  from  these  10,000 
possible  hosts,  and  Compsilura  was  also  colonized  at  the  same  time 
and  in  the  same  place  and  under  circumstances  very  much  more 
favorable  to  its  establishment  than  those  which  accompanied  its 
original  and  effective  colonization  two  or  three  years  before.  Better 
than  Compsilura  has  done  is  expected  of  none  of  the  taclunids,  and 
neither  Tricholyga,  Carcelia,  nor  Parasetigena,  nor  Zygobothria, 


232 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


which  is  the  next  parasite  to  be  considered,  has  had  the  opportunity 
which  Compsilura  has  demanded  in  each  instance  in  which  it  has 
been  colonized,  to  prove  itself  of  value. 

ZYGOBOTHRIA  NIDICOLA  TOWNS. 

Pretty  much  everything  which  has  been  said  of  Careelia  may  be 
said  of  Zygobothria,  not  so  much  because  it  is  similar  in  its  habits 
as  because  we  have  very  little  first-hand  knowledge  of  its  habits.  It 
probably  deposits  living  maggots  upon  the  body  of  its  host  or  else 
very  thin-shelled  eggs  containing  maggots  ready  to  hatch;  but  this 
is  not  certainly  known.  It  always  leaves  its  host  before  pupation 
and  forms  a  free  and  characteristic  puparium  with  roughened  surface 
and  protruding  stigmata  very  unlike  that  of  any  of  the  other  tachinid 
parasites  of  the  same  host. 

It  is  not  quite  so  common  as  a  parasite  of  the  gipsy  moth  as  is 
Careelia  and  not  so  many  have  been  colonized,  but  the  colonies  have 
been  very  satisfactory  notwithstanding,  and  there  is  about  as  much 
reason  to  expect  the  establishment  of  this  species  as  in  the  case  of 
any  of  the  others.  Like  several  of  the  others,  it  was  not  colonized 
until  1909,  and  its  recovery  is  hardly  to  be  expected  until  1911  or 
1912,  and  as  in  the  case  of  these  others  its  estabhshment  and  value 
as  a  parasite  will  very  largely  depend  upon  its  ability  to  find  a  suffi- 
cient supply  of  acceptable  hosts. 

CROSSOCOSMIA   SERICARLE  CORN. 

Many  years  have  passed  since  Dr.  Sasaki  published  the  most 
interesting  and  surprising  results  of  his  investigations  into  the  life 
and  habits  of  the  so-called  "uji"  parasite  of  the  silkworm  in  Japan, 
and  his  account  of  the  manner  in  which  this  serious  enemy  of  that 
insect  gained  access  to  its  host  was  so  extraordinary  in  the  light 
of  that  which  was  known  concerning  the  oviposition  of  tachinids  in 
general  as  to  cause  the  truth  of  his  discovery  to  be  questioned  by 
several  eminent  entomologists. 

His  work  has  been  most  carefully  reviewed  in  connection  with  the 
investigations  which  have  been  carried  on  at  the  laboratory  into 
the  life  and  habits  of  the  allied  species,  Blepharipa  scutellata,  and  it 
was  with  much  satisfaction  that  his  account  of  the  biology  of  Crosso- 
cosmia  was  found  to  apply  almost  equally  well  in  nearly  all  of  its 
details  to  the  biology  of  the  European  parasite  of  the  gipsy  moth. 
There  was  one  important  point  of  difference,  however,  in  that  the 
first-stage  Blepharipa  was  never  found  ensconced  in  the  ganglion  of 
its  host,  while  (Yossocosmia,  according  to  Dr.  Sasaki,  habitually 
chooses  this  position. 

In  1908  quite  a  number  of  the  puparia  of  a  Japanese  parasite  of 
the  gipsy  moth  was  received  from  that  country,  which,  so  far  as 


TACHTXTD  PARASITES  OF  THE  GIPSY  MOTH. 


233 


external  eharacteristics  were  concerned,  were  indistinguishable  from 
those  of  Blepharipa  from  Europe.  None  of  the  flies  issued  the 
following  spring  owing  to  the  bad  conditions  under  which  the  puparia 
were  received,  but  an  examination  of  the  pupae,  winch  like  those  of 
Blepharipa  developed  adult  characters  in  the  fall,  was  sufficient  to 
convince  Mr.  Townsend  that  the  species  was  not  lung  else  than 
Crossocosmia  sericarise  itself. 

Mr.  Townsend's  determination  of  the  species  was  partially  con- 
firmed in  the  spring  of  1910  when  several  hundred  of  the  flies  were 
reared  from  puparia  received  the  previous  summer.  Later  the  same 
year,  through  the  kindness  of  Dr.  Ivuwana,  specimens  of  the  bona 
fide  "uji"  parasites,  reared  from  silkworms,  were  received  at  the 
laboratory.  No  differences  whatever  were  discernible  and  the  con- 
firmation appears  complete. 

There  was  an  opportunity,  during  the  summer  of  1910,  to  dissect 
a  few  of  the  caterpillars  of  dispur  from  Japan,  and  among  those  so 
dissected  by  Messrs.  Thompson  and  Timberlake  were  found  several 
which  contained  the  young  larvae  of  Crossocosmia  in  the  ganglia, 
exactly  as  described  by  Dr.  Sasaki.  Thus  it  was  that  his  account  of 
the  life  of  the  "uji"  was  confirmed  in  its  every  particular  in  which 
his  remarks  were  based  upon  actual  observation  and  not  in  part 
upon  speculation  as  to  the  significance  of  certain  obscure  phenomena. 
To  Mr.  Town-end,  and  perhaps  more  particularly  to  Mr.  Thompson, 
who  has  devoted  considerable  time  and  performed  a  vast  amount  of 
tedious  and  in  some  instances  unremunerat ive  dissection  work,  i^ 
the  credit  due  for  thus  removing  all  reflection  upon  the  accuracy  of 
Dr.  Sasaki's  remarkable  observations. 

In  practically  every  respect,  except  in  the  location  of  the  first-stage 
maggots  in  the  body  of  their  Q081 .  the  life  and  habits  of  Crossocosmia 
as  a  parasite  of  the  gipsy  moth  agree  with  those  of  Blepharipa.  In 
Japan  it  is  of  about  the  same  relative  importance  as  a  parasite  as 
Blepharipa  in  Europe.  It-  habit-  of  pupation  and  the  difficulties 
experienced  in  providing  for  its  successful  hibernation  are  identical. 

Its  value  as  a  parasite  of  the  gipsy  moth  in  America  depends  very 
largely  upon  the  success  which  attends  the  attempts  to  import  and 
establish  the  European  parasite.  Should  this  be  accomplished,  a> 
now  appears  probable,  any  special  efforts  to  import  Crossocosmia 
might  well  be  deemed  unnecessary.  It  is  highly  improbable  that 
two  species  having  habits  so  exactly  similar  would  be  any  more 
effective  than  one. 

But  it  is  prett}T  evident  that  in  one  other  and  very  important 
respect  the  habits  of  Blepharipa  are  different  from  those  of  Crosso- 
cosmia. It  is  apparently  quite  as  abundant  in  Europe  as  is  Crosso- 
cosmia in  Japan,  but  even  in  the  most  important  silk-producing 
regions  it  is  yet  to  be  recorded  as  an  enemy  of  the  silkworm.  It 


234 


PARASITES  OF  GIPSY  AND  BROWX-TAIL  MOTHS. 


would  appear  that  in  their  respective  host  relations  the  two  species 
possess  a  difference,  and  it  is  probable  that  it  will  be  found  to  extend 
to  other  hosts  than  the  silkworm  when  all  the  hosts  of  both  species 
are  known.  In  consequence  it  is  not  only  well  to  have  Crossocosmia 
to  fall  back  upon  in  case  Blepharipa  fails  to  come  up  to  expectations, 
but  it  is  well  thart  it  be  given  a  trial  in  order  that  the  relative  value 
of  the  two  species  ma}7  be  determined. 

CROSSOCOSMIA  FLAVOSCUTELLATA  SCHINER  (  ?)  . 

It  was  with  considerable  surprise,  accompanied  with  no  small 
degree  of  doubt  as  to  the  accuracy  of  our  records,  that  the  presence 
of  a  species  of  Crossocosmia  was  recognized  among  the  flies  issuing 
from  European  puparia  in  the  spring  of  1910.  At  first  it  was  thought 
that  there  must  have  been  some  Japanese  puparia  mingled  with  them, 
and  when  reference  was  made  to  the  notes  it  was  found  that  some- 
thing like  15  or  20  larvae  of  Crossocosmia  sericarise  had  been  received 
the  summer  before,  and  that  their  disposition  was  not  indicated. 
Accordingly,  for  a  time  it  was  supposed  that  the  Crossocosmia  issuing 
were  from  these,  but  it  was  not  long  until  more  adults  had  issued  than 
could  possibly  be  accounted  for  in  that  manner.  There  were  as 
many  Japanese  Crossocosmia  puparia  producing  Crossocosmia  as  the 
notes  called  for,  with  never  a  Blepharipa  among  them,  and  when 
after  a  time  it  became  apparent  that  the  number  of  European 
Crossocosmia  would  run  into  the  hundreds  and  that  they  came  from 
a  variety  of  lots  of  puparia  under  several  numbers  and  received  at 
different  times,  it  was  finally  decided  that  the  existence  of  what  has 
every  appearance  of  being  an  European  race  of  C.  sericarise  could  no 
longer  be  doubted. 

Its  occurrence  in  Europe  is  the  more  surprising  because,  like 
Blepharipa,  it  has  never  been  recorded  from  the  silkworm  in  any  of 
the  silk-producing  districts.  In  its  distribution  it  also  exhibited 
peculiarities,  practically  all  that  issued  having  come  from  a  lot  of 
puparia  received  in  gipsy-moth  caterpillar  importations  from  the 
vicinity  of  Charroux,  a  town  in  western  central  France,  and  one  which 
would  hardly  be  expected  to  differ  particularly  in  its  fauna  from 
other  localities  from  which  material  was  received. 

Only  a  very  few  specimens  of  this  European  Crossocosmia  were 
pinned  for  the  collection,  but  so  far  as  the  closest  scrutiny  manifests 
there  is  not  the  slightest  structural  difference  between  the  bona  fide 
"up"  parasites  reared  from  the  silkworm — that  which  is  consequently 
believed  to  be  the  same  species  reared  from  the  gipsy  moth  in  Japan — 
and  the  species  under  present  consideration  from  France,  which  is 
seemingly  not  present,  or,  if  present,  not  common  in  other  parts  of 
Europe  from  which  parasite  material  has  been  received. 


TACHINID  PARASITES  OF  THE  GIPSY  MOTH. 


235 


The  specimens  reared,  to  the  number  of  several  hundred,  with 
several  hundred  of  the  Japanese  Crossocosmia,  were  colonized 
together,  and  under  favorable  circumstances,  as  indicated  by  the 
recovery  of  Blepharipa  from  the  immediate  vicinity  as  the  result  of 
coincidental  colonization.  Should  the  two  species  be  in  very  truth 
the  same,  they  will  probably  hybridize,  and  enough  have  been 
liberated  to  make  one  good  colony.  Should  they  refuse  to  inter- 
mingle, there  is  not  a  sufficient  number  to  make  what  past  experience 
has  indicated  as  a  "satisfactory"  colony  of  either. 

UNIMPORTANT  TA4  BIND)  PARASITES  OF  THE  OIPS1  MOTH. 

There  are  not  as  many  unimportant  dipterous  as  there  are  unim- 
portant hymenopterous  parasites  of  the  gipsy  moth  in  Europe,  and 
there  are  other  reasons  why  they  need  not  be  considered  at  so  much 
length.  One  of  them.  Pales  }>ar\da  Meig.,  which  is  occasionally 
present  in  shipments  of  gipsy-moth  caterpillars,  is  much  more  com- 
monly received  as  a  parasite  of  the  brown-tail  moth,  and  Dexodes 
nigripes  Fall.,  which  is  very  rarely  associated  with  the  gipsy  moth, 
is  a  very  common  parasite  of  the  other  host.  Both  of  these  species 
will  be  discussed  later,  and  something  will  be  said  of  their  life  and 
habits  and  of  what  has  been  done  toward  securing  their  establish- 
ment in  America. 

Of  the  remaining  tachinids  which  have  been  reared  from  imported 
material  from  Europe,  none  ha--  been  positively  associated  with  the 
gipsy  moth  itself.  There  is  always  the  chance  that  one  or  two  cater- 
pillars of  some  other  species  may  have  been  accidentally  included 
amongst  those  of  the  gipsy  moth,  and  while  the  number  of  such  has 
always  been  very  small,  the  chance  that  a  strange  parasite  should  be 
reared  from  them  rather  than  from  the  gipsy-moth  caterpillars  is 
large. 

To  date  at  least  98  per  cent  of  the  tachinid  puparia  which  have 
been  received  from  Japan  as  parasitic  upon  the  gipsy  moth  have  been 
either  of  Tachina  or  Crossocosmia.  The  remaining  1  or  2  per  cent 
have  been  of  various  species,  among  which  was  one  that  resembled 
Pales  pavida  and  another  has  been  described  as  "Compsilura-Hke." 
There  have  been  so  few  of  these  strange  forms  as  to  make  impossible 
a  definite  statement  as  to  their  host  relations.  It  seems  rather 
curious  thai  against  the  s  European  tachinids,  all  of  which  are  of  at 
Least  local  importance  as  parasites  of  the  gipsy  moth,  Japan  should 
be  able  to  produce  only  two.  It  may  be  that  the  tachinid  fauna  of 
Japan  is  much  less  extensive  than  that  of  Europe  or  of  America. 
It  may  also  be  that  a  more  thorough  survey  of  the  Japanese  situation 
will  reveal  the  presence  of  species  which  have  not  been  received 
hitherto  on  account  of  the  inadequacy  of  the  methods  of  collection 


236 


PARASITES  OF  GIPSY  AXD  BROWX-TAIL  MOTHS. 


and  shipment .  It  is  rather  expected  that  the  latter  may  be  the  true 
explanation  and  that  the  apparent  scarcity  of  tachinids  in  the  para- 
site fauna  of  the  gipsy  moth  in  Japan  may  not  prove  to  be  real. 

PARASITES  OF  THE  GIPSY-MOTH  PUPiE. 

THE  GENUS  THERONIA. 

The  discussion  of  the  pupal  parasites  of  the  gipsy  moth  ma}'  well 
begin  with  mention  of  the  most  generally  distributed  of  all — Theronia. 
The  genus  has  already  been  the  subject  of  brief  comment  in  the 
account  of  the  American  parasites,  and  something  was  said  of  the 
habits  of  Theronia  fulvescens  in  its  relation  to  this  host  in  America, 
and  of  its  unimportance.  The  form  which  by  courtesy  is  thus  specif- 
ically designated  is  very  imperfectly  differentiated  from  T.  atalantx 
Poda,  which  prevails  throughout  Europe  in  relatively  about  the  same 
abundance  in  relation  to  the  gipsy  moth.  It  is  readily  distinguished 
from  the  American  form  by  its  habitat  and  to  a  less  satisfactory 
extent  by  color. 

In  Japan  occurs  still  another,  indistinguishable  biologically  (so  far 
as  its  biology  is  known)  or  morphologically,  but  differing  in  color  from 
either  the  American,  from  which  it  is  most  distinct,  or  from  the  Euro- 
pean.   It  has  been  described  as  Theronia  japonica  Ashm. 

The  role  played  by  these  so-called  species  in  the  countries  to  which 
they  are  severally  native  is  nearly  identical  and  at  the  same  time 
unimportant,  when  economically  considered.  The  likelihood  that 
either  the  European  or  the  Japanese  would  become  relatively  more 
effective  in  America  than  the  American  itself  seems  so  very  remote 
as  to  make  unworthy  of  consideration  any  serious  attempts  to  intro- 
duce and  colonize  either.  Quite  a  good  many  of  the  European  have 
been  liberated  in  America  from  time  to  time,  but  in  a  purely  inci- 
dental way.  More  will  probably  be  received  in  the  future  and 
similarly  liberated. 

It  was  in  the  winter  of  1907-8  that  the  late  Mr.  Douglas  demons, 
of  the  laboratory,  found  a  large  number  of  the  females  of  T.  fulvescens 
congregated  beneath  old  burlap  bands  in  a  tract  of  woodland  in  which 
the  gipsy  moth  was  actively  being  fought.  Some  of  these  females 
were  dissected  some  days  later  and  found  to  be  without  fully  devel- 
oped eggs,  and  on  the  basis  of  these  inadequately  conducted  dissec- 
tions it  is  supposed  that,  as  in  Monodontomerus,  the  males  die  in  the 
fall,  leaving  the  females  to  hibernate.  It  would,  in  other  words, 
mean  that  the  species  is  single-brooded. 

The  subject  ought  to  have  been  still  further  investigated,  but  the 
unimportance  of  the  species  from  an  economic  standpoint  has  robbed 
it  of  interest  other  than  thai  which  has  attached  to  the  remarkable 
and  suggestive  vagaries  which  it  has  exhibited  in  its  host  relations. 


PARASITES  OF  GIPSY-MOTH  PUPJE. 


237 


If  it  is,  in  truth,  single-brooded,  like  its  host,  it  ought  to  multiply 
mijch  more  rapidly  than  it  has  done,  in  view  of  the  superlative 
opportunities  which  the  past  10  years  have  afforded. 

THE  GENUS  PIMPLA. 

The  several  forms  of  the  genus  Pimpla  which  have  been  reared 
from  gipsy-moth  pupae  received  from  Europe  and  Japan  are  not, 
like  the  forms  of  Theronia,  confusing  and  indefinitely  separable,  but 
good  and  distinct  species.  There  are  3  European,  and  a  like  number 
of  Japanese,  making  together,  with  the  2  American,  a  total  of  8  of 
the  genus  known  to  attack  this  host.  Notwithstanding  their  variety, 
all  the  species  acting  together  in  any  one  locality  have  never  effected 
the  degree  of  parasitism  resulting  from  the  attack  by  Theronia  in 
the  same  locality.  Being  collectively  of  so  little  importance  it  is 
unnecessary  to  say  more  concerning  their  relative  importance  indi- 
vidually. 

Quite  a  little  lias  been  learned  at  first  hand  concerning  the  two 
European  >|>e<ie>  most  frequently  encountered,  Pimpla  instigator  Fab. 
and  Pimpla  i fa  initiator  Fab.  Both  have  been  received  inconsiderable 
numbers  in  shipments  of  brown-tail  moth  pupa\  and  have  been 
liberated  to  the  number  of  several  hundred  each  in  1!)()(>,  1907,  and 
1909.     Neither  has  since  been  recovered  from  the  field. 

Both  have  been  carried  through  all  of  their  transformations  in  the 
laboratory  upon  the  gipsy  moth,  the  brown-tail  moth,  or  the  white- 
marked  tussock  moth,  and  in  the  case  of  P.  i nsti gator  upon  all  three 
above-mentioned  hosts.  The  early  stages  of  the  Larvae  have  not 
been  seen.  In  nearly  every  respect,  so  far  as  observed,  they  resemble 
each  other  in  habit  and  biology  and  also  P.  (I/ophctis)  conquisitor 
Say.  and  /\  ptdalis  Cress.,  their  American  congenors.  The  one*  point 
of  difference  between  them  i>  the  tendency  of  Pimjtfa  instigator  to 
hibernate  within  the  pupa  of  the  brown-tail  moth.  A  very  few  have 
been  reared  each  spring  since  1!)()S  from  cocoon  masses  received  the 
summer  before.    The  proportion  thus  hibernated  is  very  small. 

Pimpla  instigator,  like  the  American  P.  (Hoplectis)  amquisitor,  may 
become  hv perparasit ic  on  occasion.  On  August  7,  1907,  five  female 
specimens  of  P.  instigator  were  confined  with  several  tussock-moth 
cocoons  which  contained  the  cocoons  of  Pimpla  (Ppiurus)  inquisi- 
toriella  Dalla  Torre,  from  some  of  which  adults  were  emerging,  and 
all  of  which  had  been  spun  for  several  days.  Oviposition  was  imme- 
diately attempted.  It  was  certainly  successful,  for  on  August  29, 
at  least  two  weeks  after  the  Epiurus  had  ceased  to  issue,  a  greatly 
dwarfed  male  P.  instigator  appeared  and  it  was  followed  by  another 
similarly  small  male  on  September  3.  There  is  not  the  slightest 
doubt  that  the  European  parasite  attacked  the  native  and  that  its 
larvae  fed  to  maturity.    At  the  same  time  it  is  not  likely  that  it  would 


238  PARASITES  OF  GIPSY  AND  BROWN -TAIL  MOTHS. 

have  done  so  had  the  cocoons  of  the  native  not  been  associated  with 
the  proper  host  of  the  other. 

The  third  species,  Pimpla  hrassicarise  Poda,  is  much  less  commonly 
reared  from  either  the  gipsy  moth  or  the  brown-tail  moth  than  the 
other  two.    Apparently  its  habits  are  identical. 

Hardly  enough  have  been  received  of  the  three  Japanese  species  to 
indicate  their  relative  abundance.  The  most  striking  of  them, 
Pimpla  pluto,  appears  to  be  the  only  one  of  the  trio  which  has  been 
described,  and  to  the  others  Mr.  Viereck  has  given  the  names  P. 
disparis  and  P.  porthetrix.  It  is  possible  that  they  are  just  a  trifle 
more  common  in  connection  with  the  gipsy  moth  in  Japan  than  are 
the  corresponding  species  in  either  Europe  or  America.  At  the 
same  time  Theronia  has  outnumbered  all  three  together  in  the 
Japanese  material  studied  at  the  laboratory. 

Hardly  anything  is  known  about  them.  Not  enough  have  been 
received  to  make  colonization  possible,  and  only  upon  one  occasion 
to  permit  of  laboratory  reproduction  with  fertilized  females,  and  upon 
this  occasion  there  was  no  time  to  devote  to  their  further  study. 

Presumably,  except  for  minor  differences,  all  of  the  Japanese 
Pimpla  will  be  found  to  conform  very  exactly  in  biology  and  habit 
to  the  American  and  European.  All  will  probably  be  found  to 
attack  a  very  large  variety  of  hosts,  and  all  will  defer  their  attack 
until  their  host  has  entered  the  prepupal  or  pupal  state.  The 
females  of  all  will  probably  be  ready  to  oviposit  for  a  new  generation 
almost  immediately  following  their  emergence,  and  the  length  of  life 
cycle,  dependent  upon  temperature,  will  be  about  three  or  four  weeks. 
There  will  necessarily  be  more  than  one  generation  each  year  unless 
the  hibernating  individuals  should  live  long  enough  to  deposit  eggs 
for  another  hibernating  generation,  as  might  easily  be  possible  in  the 
case  of  Pimpla  instigator,  and  conceivably  possible  in  the  case  of 
each  of  the  others. 

Pimpla  conquisitor  and  Pimpla  pedalis  are  among  the  most 
generally  effective  of  the  pupal  parasites  of  the  medium-sized  cocoon- 
spinning  Lepidoptera  in  the  Northeastern  States.  The  first  named 
is  perhaps  the  most  common  and  effective  of  all  the  parasites  of  the 
tent  caterpillar  and  about  as  effective  as  any  other  one  as  a  parasite 
of  the  tussock  moth.  It  does  not  vary  much  in  relative  abundance 
from  one  year  to  the  next,  and  appears  to  play  a  part  which  is  rather 
to  be  compared  to  that  taken  by  the  birds  than  to  that  taken  by 
most  of  the  parasites.  It  is,  like  Theronia,  so  impartial  in  its  atten- 
tions  to  all  of  the  different  species  of  its  hosts  as  scarcely  to  be 
affected  by  an  unusual  abundance  or  unusual  scarcity  of  any  one 
among  them  in  particular. 

The  same  is  very  likely  to  be  true  of  the  European  and  Japanese 
species.    The  part  played  by  each  in  the  localities  where  it  is  native 


PARASITES  OF  GIPSY-MOTH  PUP.E. 


239 


is  probably  similar  to  that  taken  by  P.  conquisitor  or  P.  pedalis  in 
America.  On  this  account  it  is  not  considered  as  probable  that 
either  P.  examinator  or  P.  instigator  will  ever  become  established  in 
America  as  a  result  of  the  not  very  satisfactory  colonies  which  have 
been  liberated.  They  will,  of  necessity,  enter  into  direct  conflict 
with  the  American  species  for  a  share  in  the  business  of  being  para- 
site- upon  a  certain  section  of  the  insect  community,  including  a 
large  number  <>1*  species  of  which  the  gipsy  moth  is  but  one.  Compe- 
tition may  result  in  cut  rates  and  more  and  cheaper  parasitism  for  a 
time,  but  eventually,  if  the  newcomers  ever  secure  a  foothold  at  all, 
they  w  ill  either  drive  the  natives  out  of  the  business  or  else  share 
and  share  alike  with  them  in  accordance  with  an  amicable  and 
natural  agreement. 

In  consequence,  no  assistance  is  expected  from  the  various  foreign 
species  of  the  genus  Pimpla  as  parasites  of  the  gipsy  moth  or  of  the 
brown-tail  moth.  They  are  merely  liberated  when  received,  under 
the  best  conditions  wfiich  can  be  afforded  looking  for  their  estab- 
lishment, and  if  they  are  ever  recovered  from  the  field,  the  most  that 
is  expected  of  them  is  that   the  circumstances  surrounding  such 

recovery  will  exemplify  the  truth  of  the  above  remarks. 

ICHNEUMON  M8PABIS  PODA. 

One  of  the  most  distinctive  of  the  gipsy-moth  parasites,  and  one 
of  the  first,  if  not  the  very  first,  described  a--  attacking  that  host. 
Ichnevmon  disparis  is  at  the  same  time  one  of  the  less  common,  if 
dependence  is  to  he  placed  upon  the  rearing  records  at  the  labo- 
ratory. It  may  he  that  it  is  never  common,  or  it  may  be  that  it  is 
eastern  and  southern  in  its  distribution  in  Kurope,  rather  than 
central  and  western;  some  few  incidents  in  connection  with  its  impor- 
tation have  indicated  that  perhaps  its  scarcity  in  European  imported 
material  was  due  to  such  material  having  been  collected  outside  of  its 
natural  range.  In  any  event  not  more  than  two  score  of  individuals 
have  been  reared  in  the  course  of  the  five  years  since  the  work  was 
begun. 

Very  little  is  known  of  its  life  and  habits,  other  than  that  it  probably 
attacks  the  pupse  or  perhaps  the  prepup83,  and  never  the  active 
Caterpillars.  It  is  thought  possible  that  it  hibernates  as  ,111  adult, 
and  if  this  is  true,  it  might  conceivably  be  a  parasite4  of  importance 
could  enough  be  secured  to  make  possible  a  sufficiently  strong  colony. 
To  date  there  never  has  been  a  single  mated  pair  available  for  libera- 
tion a.t  any  one  time. 


240 


PAEASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


THE  GENUS  CHALCIS. 


The  first  few  boxes  of  parasite  material  which  were  received  in 
1905  produced  among  other  things  quite  a  large  number  of  Chalcis, 
a  part  of  which  issued  from  the  pupae  of  the  gipsy  moth  and  a  part 
from  dipterous  puparia,  supposed  at  that  time  to  be  those  of  tachinid 
parasites  of  the  same  host.  All  of  them  appeared  to  be  of  one  species, 
m  Ohalcis  jlavipes,  and  on  the  supposition  that  those  which  appeared 
to  issue  from  the  gipsy-moth  pupae  might  actually  have  come  from 
tachinids  which  were  inside,  all  were  destroyed. 

In  1906  and  1907  very  few  Chalcis  were  received  from  any  source 
and  there  was  no  opportunity  to  determine  the  true  host  relations 
of  the  European  species.  In  1908  a  considerable  shipment  of  gipsy- 
moth  pupae  from  Italy  arrived  in  good  condition  for  the  first  time 
since  1905,  and  another  shipment  from  Japan,  also  in  good  condition, 
reached  the  laboratory  almost  coincidently.  Both  were  soon  found 
to  contain  Chalcis  in  some  numbers,  and,  as  it  soon  developed,  in 
considerable  variety. 

It  is  not  necessary  to  go  into  any  details  as  to  the  steps  through 
which  it  was  finally  decided  that  no  less  than  six  species  of  Chalcis 
were  present  in  these  two  shipments,  of  which  two  were  easily  sepa- 
rable by  conspicuous  structural  and  color  characters.  The  others 
were  more  or  less  confusing  to  one  who  had  only  a  few  doubtfully 
identified  specimens  in  the  collection,  and  little  knowledge  of  what 
were  the  characteristics  of  a  species  in  the  genus. 

With  the  assistance  of  biological  and  geographical  characters,  the 
separation  was  finally  effected,  and  the  6  have  been  since  definitely 
identified  by  Mr.  Crawford,  as  below.  To  the  list  are  added  2  more, 
1  of  which  is  Japanese  and  the  other  American,  making  a  total  of 
8  in  all  that  have  been  definitely  associated  with  the  one  host. 

Ohalcis  Jlavipes  Panz.  Primary  parasite  of  the  gipsy  moth  in 
Europe. 

Chalcis  obscurata  Walk.  Primary  parasite  of  the  gipsy  moth  in 
Japan. 

Chalcis  caUipus  Kirby.  Primary  parasite  of  the  gipsy  moth  in 
Japan,  according  to  rearing  note  attached  to  a  specimen  forwarded 
to  the  laboratory  through  the  kindness  of  Mr.  Kuwana. 

Chalcis  fiskei  Crawf.  Parasite  of  the  tachinids  Crossocosm  in 
sericarise  and  Tachina  japonica  in  Japan,  and  thereby  a  secondary 


Chalcis  compsilurx  Crawf.  Parasite  of  Compsilura  concinnata  in 
America,  and  therefore  a  secondary  parasite  of  the  gipsy  moth. 
( Chalcis  ovata  Say  has  never  been  reared  as  a  parasite  of  the  gipsy 
moth,  although  it  is  not  improbable  that  it  will  be  found  to  attack 
it  when  the  moth  shall  extend  its  range  southward  into  territory 
where  the  Chalcis  is  more  common  than  it  appears  to  be  in  eastern 
Massachusetts.) 


PARASITES  OF  GIPSY-MOTH  PUPi. 


241 


Chalets  mimUa  L.  Parasite  upon  sarcophagids  associated  with  the 
gipsy  moth  in  Europe.  Since  the  status  of  the  sarcophagids  them- 
selves remains  to  he  determined,  it  is  impossible  to  state  that  of  the 
Chalcis.  It  is  believed  that  the  sarcophagids  are  scavengers,  and 
neutral,  in  winch  case  the  Chalcis  would  also  be  neutral. 

Chalcis  fonscolombei  Duf.  Also  a  parasite  of  sarcopnagids  asso- 
ciated with  the  gipsy  moth  in  Europe. 

Chalcis  paraphsia  Crawf.  Parasite  upon  sarcophagids  associated 
with  the  gipsy  moth  in  Japan. 

It  is  thus  seen  that  the  genus  Chalcis  is  a  little  of  everything  in 
its  relations  to  the  gipsy  moth.  Of  the  8  species,  3  are  enemies. 
2  are  friends,  and  3  are  undertaker's  assistants.  To  round  out  the 
series,  one  may  expect  t<»  find  a  Bpecies  attacking  tachinids  in  Europe, 
1  attacking  the  gipsy-moth  pupae  as  a  primary  parasite,  and  another 
attacking  sarcophagid  puparia  in  America. 

So  far  as  known  tachinids  are  Dover  attacked  by  the  species  which 
prey  upon  the  sarco- 
phagids, although  this 
stat  em  en  t  prosup- 
posesa  discriminating 
instinct  which  has 
rarely  been  encoun- 
tered among  the  par- 
asites of  the  Diptera 
generally.  For  the 
most  part,  and  in  fact 
with  no  ot  her  excep- 
tion, so  far  as  t ho  ex- 
periences of  the  lab- 
oratory havogone.  the 
parasites  which  will 
attack  the  one  will  attack  the  other  family  also.  There  are  several 
records,  including  that  already  mentioned  which  was  made  in  I'M).", 
of  the  rearing  of  Chalcis  from  tachinid  puparia,  but  these  have  either 
been  made  before  a  distinction  was  made  between  the  puparia  of 
the  two  families,  or  else  there  have  been  a  large  number  of  mixed 
tachinid  puparia  involved,  and  in  such  instances  it  is  always  possible 
and  usually  the  case  that  a  few  sarcophagids  are  present. 

As  parasites  of  the  gipsy-moth  pupa?,  Chalcis  Jlavipes  and  C. 
obscurata  are  closely  allied,  and  exceedingly  similar  in  every  respect. 
Chalcis  Jlavipes  (figs.  44,  45)  appears  to  be  rather  restricted  in  its 
range  in  Europe  and  has  never  been  received  from  any  localities 
outside  of  the  watershed  of  the  Mediterranean,  if  an  exception  is 
made  of  the  portion  of  southern  France  which  drains  into  the  Atlantic. 
The  Japanese  C.  obscurata  (fig.  46)  has  been  present  in  every  ship- 

00077°— Hull.  01 — 11  10 


Fig.  44.—  Chalcis  Jlai  tptK  A<Iult.    Enlarged.    (From  Howard.) 


242 


PARASITES  OF  GIPSY  AXD  BROWN-TAIL  MOTHS. 


Fig.  45.—  Chalcis  flavipcs:  Female 
Hind  femur  and  tibia,  showing 
markings.  Greatly  enlarged 
(From  Crawford.) 


ment  of  pupae  from  Japan,  but  the  exact  localities  from  which  these 
shipments  came  is  not  known. 

Both  are,  or  appear  to  be,  invariably  solitary,  notwithstanding 
that  there  is  an  ample  food  supply  in  one  pupa  for  several  individuals. 
Invariably  there  is  an  abundance  of  unconsumed  matter  in  the  host 
pupa,  and  on  this  account  the  parasite  has  rarely  been  successfully 
reared  from  any  of  the  imported  pupse  except  the  small  males,  in 
which  this  matter  is  in  such  small  amount  as  partially  to  dry  before 

receipt   at   the    laboratory.    In  the  large 
female  pupae  the  decomposing  contents  of 
the  pupal   shell  form   a  semiliquid  mass, 
^Sj  \     which  is  shaken  about  while  the  material  is 

in  transit,  and  completely  overwhelms  the 
larva  or  pupa  of  the  parasite.  The  parasite 
is  able  to  withstand  this  condition  to  a  re- 
markable extent,  but  not  to  the  extent  fre- 
quently brought  about  by  the  unnatural 
conditions  incident  to  transshipment. 

Partly  on  this  account,  but  still  more 
owing  to  the  difficulties  which  have  stood  in  the  way  of  securing  an 
adequate  supply  of  gipsy-moth  pupae  in  good  condition  from  localities 
where  Chalcis  occurs,  it  has  not  yet  been  possible  to  colonize  either 
the  European  or  the  Japanese  species  satisfactorily,  nor,  so  far  as 
known,  successfully.  Only  a  few  hundred  have  been  received,  all 
told,  since  their  status  as  primary  parasites 
was  first  established  in  190S.  Had  they  all 
been  of  one  species,  received  at  one  time, 
and  colonized  in  the  same  place,  there  would 
be  some  reason  to  expect  that  the  coloniza- 
tion would  be  followed  by  establishment. 
There  were  two  species,  however,  they  were 
not  all  colonized  in  one  place,  and  coloniza- 
tion has  extended  over  three  years.  The 
best  and  largest  colony  was  liberated  in  1909 
and  strengthened  by  the  addition  of  the 
small  number  received  from  abroad  in  1910. 

A  single  specimen  was  reared  from  a  lot  of  gipsy-moth  pupae  col- 
lected in  the  immediate  vicinity  of  the  colony  shortly  after  it  was 
founded  in  1909,  but  none  issued  from  similar  collections  made  in 
1910. 

Both  Chalcis  Jlavipes  and  C.  obscurata  have  been  carried  through  all 
of  their  transformations  in  the  laboratory  on  American  pupae.  The 
females  are  able  to  oviposit  very  shortly  after  emergence,  and  will  do 
so  with  considerable  freedom  in  confinement,  making  possible  the 
artificial  multiplication  of  either  species  were  it  possible  to  secure  a 


Fig.  46.  —  Chalcis  obscurata:  Fe- 
male. Hind  femur  and  tibia, 
showing  markings.  Greatly  en- 
larged.  (From  Crawford.) 


IWKASITKS  OF  (ilPSY-MOTH  PUP.E. 


243 


supply  of  host  pupse.  In  the  act  of  oviposition  the  female  firmly 
grasps  the  active  host-pupa  with  her  powerful  hind  legd  and  resists 
all  of  its  efforts  to  dislodge  her.    The  egg  has  not  been  observed  nor 


FlO.  47.— Chalcis  flavipts:  Full- 
grown  larva  from  gipsy-moth 
pupa.  Much  enlarged.  (Origi- 
nal.) 


Fig.  48.— Chalets  jtutipti: 
Pupa,  side  view.  Mucli 
en  large*  I.  (Original.) 


FIG.  49.  —  Chains  fla- 

ripts:  Papa,  ventral 

view.  Much  enlarged. 
(Original.) 


the  early-stage  larvae.  The  full-fed  larva  is  quite  characteristic  in 
appearance,  and  well  represented  in  the  accompanying  illustration 
(11^.47).    The  pupa  (figs.  48,49)  is  almost  invariably  located  in  the 


Fig.  50.— Gipsy-moth  pope,  showing  exit  holes  of  Chalcis  flauipes. 
Enlarged.   (Original  ) 

anterior  portion  of  the  host  pupa,  and  the  exit  hole  (fig.  50)  of  the 
adult  is  characteristic,  being  smaller  than  that  of  Pimpla  or  Theronia, 
and  rarely  at  the  extreme  end,  as  is  the  case  with  the  ichneumonid 
parasites.    The  pupal  exuvium  is  also  characteristic  and,  curiously 


244 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


enough,  yellow  in  the  case  of  the  Japanese,  and  black  in  that  of  the 
European  species.  Between  three  and  four  weeks  of  ordinary 
summer  weather  are  necessary  for  the  complete  life  cycle. 

The  adults  are  very  long  lived,  and  a  few  of  both  species  were  kept 
in  confinement  from  early  in  August,  1910,  until  December  of  the 
same  year.  During  this  time  they  were  offered  numerous  sorts  of 
pupae,  but  after  it  was  no  longer  possible  to  secure  those  of  the  gipsy 
moth  there  was  no  further  reproduction.  It  has  always  been  supposed 
that  it  was  the  adults  which  hibernated,  and  the  longevity  of  the 
individuals  mentioned  above  lends  strength  to  this  supposition.  If 


Fig.  51. — Monodontomcrus  xreus:  Adult  female.    Greatly  enlarged.  (Original.) 


correct,  there  need  be  only  a  single  generation  annually,  and  the 
species  would  therefore  be  independent  of  any  other  host.  Neither 
is  known  to  attack  the  brown-tail  moth,  but  both  have  been  reared 
through  their  transformations  upon  pupae  of  the  white-marked 
tussock  moth. 

Both  of  the  species  of  Chalcis  are  of  considerable  importance  as 
parasites  of  the  gipsy-moth  pupa)  in  their  respective  habits,  and  so 
far  there  lias  nothing  occurred  to  destroy  confidence  in  their  ability  to 
become  of  importance  here  provided  a  sufficiently  large  number  may 
be  seen  rod  to  enable  them  to  become  established.  It  is  confidently 
expected  that  they  will  disperse  at  a  very  rapid  rate,  and  on  this 
account  it  will  be  necessary  that  the  colonies  be  large  and  strong,  so 
that  extinction  through  too  great  scarcity  during  the  first  or  second 
season  following  colonization  will  not  result.  Renewed  efforts  to 
make  this  possible  will  be  made  this  coming  season,  and  at  the  same 


Fig.  2.— "Sifting"  Gipsy-Moth  Eggs  for  Examination  as  to  Percentage  of 
Parasitism.   I  Original.) 


PARASITES  OF  GIPSY-MOTH  PUPJE. 


245 


time  special  efforts  will  be  made  to  recover  the  species  from  the  held 
as  a  result  of  earlier  colonization. 

IfOKODONTOMEBUS  J5KEUS  WALK. 

Few  anions  the  parasites  have  been  the  cause  of  a  larger  variety  of 
mingled  feelings  than  this,  and  the  history  of  its  introduction  into 
Massachusetts  is  in  many  respects  unique  and  apart  from  similar 
histories  of  the  other  parasites. 

The  females  (fig.  51)  have  the  curious  hahit  of  hibernating  in  the 
winter  webs  of  the  brown-tail  moth,  and  the  species  is  rather  a 
parasite  of  the  brown-tail  moth  pupae  than  of  the  gipsy-moth  pupae, 
although  it  is  sometimes  common  in  the  latter  connection  as  well. 
It  was  first  received  at  the  laboratory  in  the  winter  of  1905  in  ship- 
ments of  brown-tail-moth  hibernating  nests  and  was  reared  from 
these  nests  in  the  spring.  It  has  be<  n  recorded  as  a  parasite  of  the 
gipsy  moth,  and  a  colony  was  planted  by  Mr.  Titus  early  in  the 
spring  of  l'.HM).  The  records  of  this  colony  have  apparently  been  lost 
and  it  will  never  be  known  exactly  how  many  individuals  were 
Included  in  it . 

Some  1,700  issued  from  the  imported  nests  that  first  spring,  but 
not  all  of  them  were  liberated.  Dr.  VY.  II.  Ashniead.'  to  whom  the 
specimens  were  sent  for  determination,  stated  it  as  his  opinion  that  it 
was  a  secondary  parasite  rather  than  a  primary,  since  few  or  none  of 
the  group  to  which  it  belonged  were  definitely  known  to  be  primary 
parasites  upon  lepidoptefOUS  bosts.  Accordingly  the  work  of  coloni- 
zation was  stopped  almost  as  soon  as  it  was  begun,  and  for  a  period 
of  more  than  two  years  Monodontonierus  was  treated  a<  a  secondary 

parasite,  and  destroyed  whenever  found.    During  this  period,  many 

thousands  issued  from  importations  of  brown-t  ail-niot  h  cocoons,  and 
much  doubt  was  felt  as  to  its  actually  being  a  secondary,  on  account 
of  the  numbers  alone,  since  it  enormously  outnumbered  all  other 
hymenopterous  parasites  (whether  primary  or  secondary)  reared. 
For  reasons  which  would  be  obvious  to  anyone  who  has  ever  had  any 
experience  in  handling  the  cocoons  of  the  brown-tail  moth,  no  serious 
effort  was  made  to  determine  its  host  relations  by  the  dissection  of 
the  brown-tail  moth  pupa*.  A  few  pupa!  were  sought  out  from 
which  it  had  issued,  and  no  trace  of  any  other  host  was  found,  but 
such  was  the  state  of  our  technical  knowledge  at  that  time  as  to 
render  questionable  such  evidence.  We  were  not  sufficiently 
familiar  with  the  appearance  of  pupae  from  which  Monodontonierus  as 
a  secondary  parasite  had  issued,  and  dared  not  give  any  more  than 
negative  weight  to  the  fact  that  no  remains  of  any  other  primary 
host  than  Monodontonierus  could  be  found.  Moreover,  against  this 
negative  evidence  indicative  of  primary  parasitism,  was  much  that 


1  Now  deceased. 


246 


PARASITES  OF  GTPSY  AND  BROWN-TAIL  MOTHS. 


was  positive,  indicative  of  secondary  parasitism,  because  every  little 
while  the  Monodontomerus  would  issue  from  tachinid  puparia  which 
had  been  sorted  out  from  the  cocoons  and  pupae.  Still  more  fre- 
quently it  was  reared  from  puparia  of  sarcophagids. 

In  the  summer  of  1908  the  shipment  of  gipsy-moth  pupae  from 
Italy,  which  served  the  purpose  of  establishing  the  status  of  the 
European  species  of  Chalcis  in  their  relation  to  the  gipsy-moth, 
served  also  in  establishing  the  status  of  Monodontomerus  as  a  primary 
parasite  of  this  host.  A  large  number  of  the  pupae  which  were 
examined  was  found  fdled  with  the  larvae  (fig.  53)  or  pupae  (figs. 
54,  55)  of  the  parasite,  and  even  when  the  larvae  were  still  immature 
and  feeding  there  was  absolutely  no  trace  of  any  other  parasite  present 
in  the  majority  of  instances.  There  was  such  trace  in  a  few,  and  it 
was  found  that  the  former  presence  of  Pimpla,  Theronia,  or  any 
tachinid  was  very  easy  of  determination,  no  matter  how  completely 
it  might  have  been  destroyed. 

It  was  felt  that  a  mistake  had  been  made  in  not  liberating  the  very 
large  number  of  Monodontomerus  which  had  been  secured  through 
the  earlier  shipments,  and  it  was  resolved  to  colonize  them  as  fast  as 
they  were  secured  in  the  future.  Hardly  anything  was  less  expected 
than  that  the  species  should  even  then  be  established. 

Each  winter  since  that  of  1906-7  (PI.  XXI)  large  numbers  of  the 
winter  nests  of  the  brown-tail  moth  had  been  collected  in  a  vain 
endeavor  to  secure  evidences  of  the  establishment  of  Pteromalus 
egregivs,  but  without  results.  In  the  winter  of  1908-9  this  work  was 
undertaken  anew,  and  almost  the  first  lot  which  was  brought  into  the 
laboratory  was  shortly  productive  of  a  number  of  Monodontomerus, 
exactly  as  lots  collected  in  the  open  in  Europe  had  been  productive 
of  the  species  each  season  since  their  importation  had  been  begun. 
The  circumstance,  surprising  and  unexpected,  was  also  gratifying, 
coming  as  it  did  so  soon  after  the  investigations  which  had  served  to 
demonstrate  the  primary  parasitism  of  the  species.  The  surprise  and 
gratification  was  increased  materially  when  it  was  discovered,  through 
the  collection  of  a  large  quantity  of  the  winter  webs,  that  the  parasite 
was  distributed  over  a  considerable  territory  indicated  by  the  area  I 
on  the  accompanying  ma])  (PI.  XXII),  and  though  the  actual  number 
recovered  was  small,  the  rapid  rate  of  dispersion  was  sufficient  to 
indicate  a  very  rapid  rate  of  increase.  It  was  estimated,  in  fact,  that, 
at  least  a  25-fold  per  year  increase  and  a  10-mile  per  year  dispersion 
had  followed  the  colonization  three  years  before. 

In  L909  .in  examination  of  the  pupae  of  the  gipsy  moth  in  the  held 
revealed  the  presence  of  what  was  actually  a  small,  but  under  the  cir- 
cumstances  a,  gratifyingly  Large,  uumber  which  contained  the  larvae  or 
pupa*  of  the  parasite,  and  the  results  of  the  winter  scouting  work  were 
awaited  with  confidence  and  interest.    They  were  quite  as  satisfac- 


PAKASITKS  OF  OIPSY-MOTII  PITT.. 


247 


ton'  as  could  bo  expected.  The  collections  of  nests  from  areas  II  and 
1 1 1  on  the  map  I  PL  XXII)  produced  the  parasite  in  abundance,  and  in 
area  I,  throughout  which  it  was  found  the  winter  before,  it  was  very 
much  more  abundant,  as  will  be  seen  by  reference  to  the  tabulated 
summary  of  the  results  of  the  work  for  the  winter  in  Table  X. 


Table  X.  —  Monodontomerus  a  r<  iu  as  distributed  oxer  its  area  of  dispersion.1 


Section. 

Year. 

Number 
of  brown- 
tail  MSta 
collected. 

Number 
of  Mono- 
donto- 
merus 
recovered. 

Monodon- 
tamerm 
per  1 .000 
bmwn- 

tail  Deals, 

Beetlon. 

Year. 

Number 
of  brown- 
tail  Ile-ts 

collected. 

Number 
of  Mono- 
don  to- 
merns 
recovered. 

Monodon- 
tomeroa 

per  1  .000 

brown- 
tail  nests. 

1908 

B,  "7  1 

39 

6 

4 

1910 

1 .  e;«is 

234 

137 

1  1 

1909 

2.200 

70s 

tn 

5 

1910 

701 

215 

305 

1910 

1,508 

495 

328 

6 

1910 

2,836 

521 

183 

l'.MIS 

1909 

947 

0 

0 

1910 

1,050 

260 

246 

2 

1.107 

124 

112 

8 

1910 

555 

86 

151 

1910 

700 

1VJ 

260 

9 

1910 

S25 

538 

652 

/  1909 

770 

34 

4«.» 

10 

1910 

500 

1 

2 

3 

\  1910 

200 

13 

50 

11 

1910 

1,600 

95 

59 

'  Refer  to  the  map  ( I'l.  XXII)  for  the  area  included  in  each  section. 


Tahi.k  IIkpi:kskntin<;  tiik  Rump  Mi  i.tiim.ic vtk >n  i.k  MmVudhxtomeki-s  i.v  the  Field. 


Brown-tail 
nests  col- 
lected. 

Monodon- 
tomerus 
recovered. 

Monodon- 
tonierus 
per  1  ,(XH> 

brown-tail 
nests. 

1,927 
960 

168 
190 

87 
199 

In  HUD  a  fairly  sat i>faet <>ry  number  of  the  parasites  was  reared 

from  collections  of  br<>wn-tail  moth  cecoons  made  in  the  field,  but 

when  the  gipsy-moth  pup»  were  examined  in  the  field  as  in  1909, 
scarcely  if  any  more  were  found  to  be  parasitized.  This  was  any- 
thing but  encouraging,  because  it  had  been  expected  that  parasitism 
would  amount  to  at  least  1  per  cent,  if  the  rate  of  increase  which  had 

prevailed  up  to  1909  had  continued.  It  appeared  that  the  Monodon- 
tomerus  was  either  inclined  to  pass  over  the  gipsy-moth  pupae  in 
favor  of  other  hosts,  or  else  that  its  rate  of  increase  had  received  a 
sudden  check  before  it  was  sufficiently  abundant  to  become  of  aid  in 
decontrol  of  the  moth.  As  before,  that  winter's  work  was  anticipated 
with  interest  since  its  results  would  be  more  directly  comparable  with 
those  of  the  year  before  than  was  that  summer's  work. 

The  collections  of  winter  webs  were  first  made  in  the  territory 
included  within  the  range  of  the  parasite  in  the  winter  of  1909-10 
(areas  I,  II,  and  III),  and  the  fact  soon  became  manifest  that  instead 
of  increasing  it  had  actually  decreased  in  abundance  throughout  that 
territory  in  the  course  of  the  year.  It  was  inexplicable,  in  view  of  the 
unlimited  opportunities  for  increase,  and  it  was,  to  say  the  least, 
discouraging. 


248 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Following  these  preliminary  collections,  which  were  intended  for  no 
other  purpose  than  to  indicate  the  rate  of  increase,  collections  from 
towns  and  cities  to  the  westward  of  its  known  distribution  the  previ- 
ous winter  and  to  the  northward  in  southern  New  Hampshire  and 
southernmost  Maine  were  made.  It  was  rather  confidently  expected 
that  it  would  be  found  in  Maine  just  over  the  New  Hampshire  line, 
and  also  that  this  would  mark  the  limits  of  its  distribution  in  that 
direction. 

How  far  removed  the  expectations  were  from  the  reality  is  well 
indicated  b}^  the  accompanying  map 1  (PL  XXIII) ,  and  still  more  by  a 
study  of  the  table.  It  will  be  seen  that  instead  of  stopping  at  the  Maine 
State  line,  Monodontomerus  has  extended  its  range  for  a  full  hundred 
miles  to  the  northeastward,  and  that  to  the  north  and  west  it  has  pretty 
nearly  reached  the  limits  of  the  present  known  distribution  of  the 
brown-taii  moth  itself.  But  what  is  more  surprising,  it  is  actually 
much  more  abundant  in  a  large  part  of  this  new  territory  than  it  was 
in  Massachusetts  a  year  before. 

It  will  also  be  observed  that  the  distribution  has  been  much  more 
rapid  toward  the  north  and  east  than  toward  the  west  and  south, 
winch  is  true  also  of  that  of  the  gipsy  moth  and  the  brown-tail  moth. 
Whether  tins  will  prove  to  be  the  rule  with  others  of  the  parasites 
remains  to  be  seen.  It  is  not  indicated  in  the  instance  of  any  other 
as  yet. 

Monodontomerus  appears  to  pass  through  but  a  single  generation 
annually.  The  females  are  sometimes,  perhaps  habitually,  fertilized 
before  they  actually  issue  from  the  pupal  shell  of  the  host.  The 
males  invariably  die  before  the  winter,  or  at  least  out  of  many  thou- 
sands of  individuals  which  have  been  secured  in  the  winter  from 
brown- tail-moth  nests  at  home  and  abroad,  only  females  have  been 
present.  Dissection  of  a  considerable  number  of  hibernating  females 
has  failed  to  result  in  the  finding  of  even  partially  developed  eggs. 
Neither  has  it  been  found  possible  to  keep  females  alive  in  the  spring 
until  eggs  should  develop,  although  some  have  remained  in  a  state 
of  activity  in  confinement  for  several  months. 

Beginning  in  1906,  and  each  year  thereafter  until  1900,  numerous 
attempts  wore  made  to  secure  reproduction  in  confinement.  Dipter- 
ous larvae  and  puparia  as  well  as  pupae  of  the  gipsy  moth  and  the 
brown-tail  moth  were  supplied  as  hosts,  and  females  from  hibernating 
nests  as  well  as  those  from  gipsy-moth  and  brown-tail  moth  pupae 
and  other  sources  were  used  in  these  experiments.  Failure  resulted 
in  every  instance,  due,  apparently,  to  the  impossibility  of  keeping 
the  parents  alive  until  eggs  should  be  developed. 


1  The  maps  and  tables  have  been  prepared  by  Mr.  TI.  E.  Smith,  to  whom  the  work  of  caring  for  the  nests 
us  they  have  been  received  at  the  laboratory  has  largely  been  intrusted. 


PARASITES  OF  GIPSY- MOT II  PUP.E. 


249 


The  egg  which  is  figured  (fi*r.  52)  was  dissected  from  a  female  which 
was  imported  in  1909  with  cocoon  masses  of  the  brown-tail  moth  and 
which  was  evidently  hibernated.  She  was  ^iven  no  opportunity  to 
oviposit.  In  1910  several  females  were  collected  in  the  open  in  June, 
and  these,  upon  beiii£  supplied  with  fresh  pupae  of  the  brown-tail 
moth,  immediately  oviposited. 

The  very  characteristic  larvae  (fig.  53)  feed  externally  upon  the 
pupje  of  taehinids  within  the  puparium,  hut 
internally  within   the  pupa*  of  Lepidoptera. 
The  pupa?  (figs.  54,  55)  are  also  characteristic,  ^S^^^S^g 
and  the  appearance  of  that   of  the  female  i-    na.82.  Uonoiontomer** 
indicated  by  the  accompanying  illustrations.     *reus:  B»  (iro;1,l-v  pn- 

X     /r>  «  m     .      i%         •  larged.  (Original.) 

The  exit  hole  (fig.  50)  Jell   m  the  e;ipsy-moth 

puptB  IS  invariably  smaller  than  that  left  by  Chalcis,  and  Larger  than 
that  of  Diglochis.  It  may  be  located  anywhere,  in  which  respect  it 
differs  from  any  of  the  Larger  of  the  pupa]  parasites. 

As  a  secondary  parasite;  Monodontomerus  has  been  reared  from 
tachinid  puj)aria  upon  numerous  occasions  both  from  those  which 
have  been  received  from  abroad  and  from  those  collected  in  America. 
It  Was  rather  expected  «»f  it  that  its  attack  would  be  confined  to  those 


FlG.  53.  MnnodonlnvKTiis 
sermx:  Larvi..  <; really 
enlarged.  (Original.) 


Fig.  54.  Monodonlomeras 
serevs:  Pupa,  side  view. 
Greatly  enlarged. 
(Original.) 


Fig.  55.—  Monodonto- 
mrrus  xreus:  I'upa, 
ventral  view.  Great- 
ly enlarged.  (Orig- 
inal.) 


which  were  immediately  associated  witli  one  or  another  of  its  chosen 
hosts,  but  as  usual  it  did  the  unexpected,  and  it  has  been  reared  from 
Conipsilura  puparia  which  were  collected  at  the  base  of  trees  upon 
which  the  caterpillars  of  the  gipsy  moth  had  been  common.  It  has 
also  been  reared  from  taehinids  parasitic  upon  the  tussock  moth  (and 
from  the  tussock  moth  as  a  primary  parasite),  from  the  tent  cater- 
pillar, in  which  it  was  apparently  parasitic  upon  Pimpla,  and  from 
the  cocoons  of  Apanteles  lacteicolor  Vier.,  the  imported  brown-tail 
moth  parasite.    Like  another  anomalous  species,  Pteromalus  egregius, 


250 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


it  betrays  a  distinct  partiality  for  anything  that  savors  of  the  brown- 
tail  moth.  It  is  thereby  led  to  seek  out  the  molting  webs  of  the 
brown-tail  caterpillars  in  the  spring  and  consequently  comes  into 
contact  with  the  Apanteles  cocoons. 

THE  SARCOPHAGIDS. 

There  has  been  considerable  controversy  in  the  past  concerning 
the  habits  of  the  Sarcophagidae,  and  a  wide  difference  of  opinion  as 
to  whether  they  were  to  be  considered  as  truly  parasitic,  or  whether 
they  were  merely  scavengers,  attacking  and  feeding  upon  insects 
which  had  died  through  some  other  cause.    In  the 
case  of  those  species  which  are  reared  from  grass- 
hoppers there  seems  to  be  no  further  question  that 
they  are  to  be  classed  as  true  parasites  or  at  least 
that  they  are  as  truly  parasitic  as  many  of  the  more 
degraded  among  the  hymenopterous  parasites.  This 
seems  not  to  have  been  proved  of  any  of  the  species 
which  are  found  within  the  pupae  of  the  larger 
Lepidoptera. 

If  judgment  were  to  be  based  upon  the  occurrence 
of  sarcophagids  in  the  shipments  of  gipsy-moth 
fig.  56.  — Gipsy -moth  pupae  from  abroad,  it  would  certainly  be  judged  that 
hoiea'ieft10byng3fono-  the  sarcophagids  were  parasitic.     Their  puparia 
dontomerus  xreus.  (p}.  XX,  fig.  3),  have  frequently  outnumbered  the 
Enlarged.  (Ongmai.)  ^acnmj(|  pUparia?  anc[  even  the  tachinid  puparia  and 
hymenopterous  parasites  together.    Unfortunately,  there  is  nothing 
known  of  the  circumstances  under  which  this  material  was  collected 
in  any  instance,  and  for  all  that  is  known  to  the  contrary,  the 
sarcophagids  actually  entered  gipsy-moth  pupae  which  had  been  at- 
tacked and  killed  by  another  parasite,  Chalcis  for  example,  and  by 
feeding,  first  upon  the  uncons timed  contents  of  the  pupal  shell,  and 
later  upon  the  body  of  the  true  parasite,  which  might  be  destroyed 
either  through  accident  or  design  on  the  part  of  the  intruder,  would 
become,  in  effect,  secondary  parasites. 

If  judgment  were  to  be  based  upon  the  results  of  a  quite  elaborate 
series  of  investigations  into  the  relations  between  the  native  sarco- 
phagids and  the  gipsy  moth  in  America,  it  would  unavoidably  be  to 
the  effect  that  these  sarcophagids  were  scavengers  and  nothing  more. 
We  are  confronted  with  conflicting  evidence,  presented  by  a  much 
greater  abundance  of  sarcophagids  associated  with  the  gipsy  moth  in 
Europe  than  is  similarly  associated  with  it  in  America,  which  is  sug- 
gestive of  two  things:  Either  the  sarcophagids  arc  associated  with  the 
gipsy  moth  because  they  sire  parasitic  upon  it  or  because  of  the  pres- 
ence of  its  parasites,  which  is  quite  as  reasonable  an  explanation.  It 
will  require  much  careful  work  in  Europe  before  it  will  be  possible  to 


PARASITES  OF  GIPSY-MOTH  PUP*:. 


251 


settle  this  point  at  all  definitely.  Meanwhile  it  does  not  seem  to  be 
advisable  to  attempt  the  introduction  of  the  European  sarcophagids 
until  we  know  whether  they  are  an  aid  in  the  control  of  the  moth  or  a 
possible  hindrance  to  the  work  of  the  parasites. 

The  special  investigations  which  were  conducted  for  the  purpose 
of  detennining  the  exact  status  of  the  sarcophagids  in  America  in 
relation  to  the  gipsy  moth  were  conducted  by  Mr.  T.  L.  Patterson, 
and  have  been  made  the  subject  of  a  special  report.1 

Another  aeries  of  investigations,  conducted  by  Mr.  P.  IT.  Timber- 
lake  upon  the  parasites  of  the  pine  "  tussock  moth''  in  northern 
Wisconsin,  resulted  in  the  accumulation  of  evidence  which  pointed 
epiite  convincingly  to  the  parasitic  character  of  certain  sarcophagids 
which  he  encountered  in  abundance4  associated  with  this  insect. 
Unfortunately  it  is  not  wholly  convincing.  K  it  could  be  accepted 
at  its  full  face  value  it  would  mean  that  in  these  flies  we  have  a  group 
of  dipterous  parasites  wholly  distinct  from  the  tachinids,  and  working 
in  a  wholly  different  manner.  Tlx4  tachinids  are  caterpillar  parasites, 
and  never,  so  far  as  has  been  recorded,  attack  the  caterpillar  after  it 
has  spun  for  pupation.  The  sarcophagi-,  like  Pimpla,  Theronia, 
etc.,  are  pupal  parasites  and  w  ill  be  grouped  together,  i.nd  at  the  same 
time  apart  from  the  hyinenopteroiis  pupal  parasites,  even  as  the 
tachin'uU  a>  a  group  stand  beside  but  apart  from  the  hyinenopteroiis 

parasites  of  the  caterpillars. 

THE  PBJSDA4  BOlTfl  BEETLES. 

It  is  very  probable  that  further  studies  into  the  subject  of  natural 
predatory  enemies  of  the  gipsy  moth  will  result  in  the  addition  of  a 

considerable  Dumber  of  names  to  the  list  of  predaceous  beetles  which 
attack  it  in  one  stage  or  another  of  its  existence  and  with  more  or 
less  freedom.  The  egg  masses  received  from  abroad  have  very  fre- 
quently been  infested  with  small  dermestids, and  in  the  forests  in  the 
vicinity  of  Kief.  Russia,  in  September,  1910,  large  numbers  of  the 
larva1  >f  a  species  not  yet  determined  were  found  feeding,  to  all 
appearances,  upon  the  eggs  of  the  moth  as  well  as  upon  the  covering 
of  felted  hair. 

That  these  larvae  do  actually  ea1  the  eggs  was  demonstrated  by  Mr. 
Burgess  during  his  association  with  the  moth  work  as  conducted  by 
the  State  board  of  agriculture  in  1899  and  later  his  observations  were 
confirmed  by  a  series  of  simple  experiments  conducted  at  the  labora- 
tory. 

In  the  spring  of  1908  a  large  number  of  cocoons  of  the  tussock  moth 
with  egg  masses  attached  was  collected  in  East  Cambridge,  Mass., 
and  from  them  in  dune4  a  number  of  dermestid  beetles  issued,  deter- 

>U.S.  Department  of  Agriculture,  Bureau  of  Entomology,  Technical  Series  19,  Part  III,  March  22, 1911. 


252 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


mined  by  Mr.  E.  A.  Schwarz  as  Anthrenus  varius  Fab.  and  Trogo- 
derma  tarsale  Melsh.  The  Trogodercna  was  the  more  common  of  the 
two.  Later,  in  the  fall,  another  collection  of  old  cocoons  was  made 
for  the  purpose  of  determining  the  status  of  these  beetles.  It  was 
found  that  both  of  them  fed,  as  larvae,  upon  the  eggs  of  the  tussock 
moth,  and  when  they  were  confined  in  vials  with  eggs  of  the  gipsy 
moth  they  fed  not  only  upon  the  hairy  covering  of  the  egg  masses, 
but  also  upon  the  eggs  themselves.  Larvae  apparently  of  one  of  these 
species  have  several  times  been  received  at  the  laboratory  associated 
with  egg  masses  of  the  gipsy  moth,  which  were  in  each  instance  col- 
lected upon  the  sides  of  buildings  or  in  other  situations  different  from 
those  under  which  egg  masses  are  most  frequently  encountered. 

As  soon  as  the  gipsy-moth  caterpillars  hatch,  if,  as  frequently  hap- 
pens, the  egg  mass  is  situated  in  some  particularly  well-sheltered  spot, 
the  young  caterpillars  are  liable  to  attack  by  small  carabid  beetles, 
several  species  of  which  have  been  found  under  burlap  bands  in  the 
spring  apparently  feeding  upon  the  gipsy-moth  caterpillars  in  this 
stage.  Several  of  these  species  were  made  the  subject  of  casual  study 
in  the  summer  of  1910,  the  results  of  which  will  be  published  later. 

The  elaterid  genus  Corvmbites,  though  not  generally  recognized 
as  predaceous,  is  undoubtedly  more  or  less  addicted  to  a  diet  of  living 
insects.  An  adult  of  one  species  was  once  found  feeding  upon  the 
cocoons  of  Apanteles  fulvipes;  and  the  larva  of  another,  upon  one  occa- 
sion, at  least,  upon  the  pupae  of  the  gipsy  moth.  There  are  many 
species  in  the  New  England  States.  Some  of  them  are  nocturnal, 
and  it  is  not  at  all  beyond  the  limits  of  probability  that  they  may  be 
found  listed  among  the  predatory  enemies  of  the  gipsy  moth  and  the 
brown-tail  moth  when  these  lists  shall  have  been  finally  completed. 

Among  the  coccinellids  the  large  Anatis  15-punctata  Oliv.  has  more 
than  once  been  observed,  as  a  larva,  attacking  the  small  caterpillars 
of  the  gipsy  moth,  and  it  is  not  at  all  unlikely  that  the  species  is  actu- 
ally of  as  much  consequence  as  some  of  the  minor  parasites  in  assist- 
ing in  the  control  of  the  pest. 

The  lampyrids,  too,  include  amongst  their  numbers  many  species 
which  are  either  occasionally  or  habitually  predatory.  One  such 
which  abounds  in  eastern  Massachusetts  in  the  spring  flying  about  in 
the  tops  of  the  trees  and  crawling  over  the  foliage  was  encountered 
in  the  spring  of  1910  in  the  act  of  destroying  a  small  gipsy-moth 
caterpillar.  Probably  one  beetle  would  not  destroy  many  cater- 
pillars in  the  course  of  its  life,  but  there  are  such  swarms  of  the  beetles 
as  to  make,  an  average  of  even  one  caterpillar  count  materially  in  the 
end.  Some  of  the  Lampyrids  are  nocturnal,  as  infact  are  a  great  many 
of  the  proved  or  probably  predatory  Coleoptera,  and  their  association 
with  the  gipsy  moth  is  riol  likely  to  be  established  unless  special  effort 
toward  thai  end  is  undertaken.    Such  studies  require  time  and  pa- 


PARASITES  OF  GIPSY-MOTH  PIT.E. 


253 


tience,  but  are  none  tlie  less  necessary  if  we  are  ever  to  know  all  that 
is  to  be  known  about  the  subject. 

None  of  the  beetles  mentioned  is  likely  to  attack  the  later-stage 
caterpillars,  but  among  the  larger  Carabida?  is  to  be  found  a  variety 
oi  species  which  arc  not  only  able,  but  more  than  willing  to  destroy  the 
lull-fed  caterpillars  and  pupae  whenever  opportunity  offers.  There  are 
many  such  in  Europe  which  do  not  occur  in  America,  and  altogether 
a  considerable  number  of  different  species  has  been  received  from 
abroad  and  tested  as  to  ability  to  assist  in  the  control  of  the  gipsy 
moth  in  this  country. 

Three  characterisl  ics  in  addit  ion  to  ability  and  willingness  to  attack 
the  gipsy  ninth  are  necessary  if  the  introduction  of  a  beetle  is  to  be 
seriously  undertaken  as  an  economic  experiment.  It  must  breed  at 
the  proper  season  of  the  year,  so  that  its  larva1  may  receive  the  ad- 
vantage of  the  practically  unlimited  food  supply  which  the  present 
superabundance  of  the  gipsy  moth  gives:  it  must  be  able  to  with- 
stand the  rigors  of  the  New  England  climate,  and  not  only  the  adult 
beetles  but  their  young  must  be  arboreal  in  habit.  An  abundance 
of  species  both  native  and  foreign  will  feed  freely  upon  the  gipsy 
moth  in  confinement,  but  of  these  only  a  few  will  seek  out  the  cater- 
pillars or  pupa?  in  the  situations  in  which  they  are  to  be  found  in 
America.  The  adults  of  a  port  ion  of  t  his  number  do  habitually  climb 
into  the  trees  in  search  of  their  prey,  but  not  all  such  are  similarly 
arboreal  during  their  larval  stages.  Of  those  which  are  arboreal,  or 
which  appear  to  be  arboreal,  during  all  of  their  active  life,  a  part 
appear  to  breed  at  the  wrong  season  of  the  year  and  another  part  do 
not  extend  their  range  into  a  sufficiently  high  Latitude  to  make  them 
effective  as  enemies  of  the  gipsy  moth.  There  is  not  a  single  species 
native  to  America  which  meets  all  of  the  delicate  requirements  of  the 
situation,  but  such  a  species  has  been  found  abroad  in  Calosoma  si/co- 
phanta  L.  (See  PI.  I,  frontispiece,  adult  eggs,  larva1,  and  pupa.)  This, 
of  all  of  the  numerous  species  of  predaeeous  beetles  which  have  been 
investigated  at  the  laboratory,  bids  fair  to  be  of  real  assistance  in 
the  fight  which  is  being  waged. 

Like  all  the  larger  carabids  inhabiting  the  temperate  regions,  this 
species  is  terrestrial  during  a  considerable  portion  of  its  life  cycle,  but 
both  adults  and  young,  which  are  equally  voracious,  climb  freely  into 
the  trees  in  search  of  their  prey.  The  eggs  are  deposited  in  the  earth, 
and  the  young  larvae  upon  emerging  are  possessed  of  a  remarkable 
vitality  and  sufficient  strength  and  cunning  to  enable  them  to  seek 
out  and  successfully  to  attack,  when  found,  the  largest  and  most 
active  of  the  gipsy-moth  caterpillars.  They  also  attack  the  pupae 
with  even  greater  freedom,  and  once  ensconsed  within  such  a  mass 
of  pupa1  as  is  frequently  encountered  in  partially  protected  situations 
upon  a  badly  infested  t  ree,  will  rapidly  complete  their  growth  without 


254  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

leaving  the  spot.  The  full-fed  larvse  seek  the  earth  and,  burrowing 
well  below  the  surface,  construct  a  vaulted  pupal  cell,  within  which 
the  final  transformation  takes  place  during  the  late  summer  or  fall. 
The  adult  beetles  remain  quiescent  and  as  a  rule  do  not  issue  until 
late  in  the  succeeding  spring. 

The  breeding  season  coincides  almost  exactly  with  the  caterpillar 
season.  The  hibernated  beetles  begin  egg  deposition  just  a  little 
before  the  caterpillars  are  large  enough  to  be  easily  found  and  attacked 
by  their  }Toung;  the  height  of  their  activities  in  this  direction  is  at  a 
time  when  their  young  are  best  provided  for,  and  they  cease  oviposi- 
tion  very  shortly  after  the  gipsy  moths  themselves  begin  to  deposit 
eggs  for  a  new  brood.  Very  shortly  thereafter,  with  summer  still 
at  its  height,  the  adult  beetles,  both  male  and  female,  burrow  deep 
into  the  soil  and  become  dormant,  awaiting  the  arrival  of  another 
spring. 

The  data  as  given  above  concerning  the  life  and  habits  of  Calosoma 
sycoplmnta  have  been  accumulated  by  Mr.  A.  F.  Burgess,  who  has 
had  full  charge  of  that  part  of  the  laboratory  work  which  had  to  do 
with  the  predatory  beetles  since  the  late  summer  of  1907.  Up  to 
that  time  the  pressure  of  other  work  was  so  great  as  to  render  impos- 
sible any  systematic  studies  along  that  or  similar  lines.  The  first  of 
the  adult  beetles  of  this  species,  together  with  a  smaller  quantity  of 
another,  Calosoma  inquisitor  L.,  were  imported  and  in  part  liberated 
in  the  spring  of  1906.  A  few  were  confined  within  the  large  out-of- 
door  cages  of  the  type  already  figured  and  briefly  described  (see  PI. 
XIV),  and  reproduction  was  secured  in  the  instance  of  Calosoma 
sycopJianta.  Neither  Mr.  Titus  nor  Mr.  Mosher  was  able  to  give  this 
phase  of  the  work  the  attention  which  it  really  deserved,  and  while 
their  observations  were  sufficient  to  cover  most  of  the  salient  points 
in  the  life  history  of  the  predator,  there  was  still  an  abundance  of 
opportunity  for  further  studies. 

In  1907  early  and  not  very  systematic  surveys  of  the  several  field 
colonies  established  by  Mr.  Titus  the  year  before  failed  to  result  in 
the  recovery  of  the  beetle.  Accordingly,  when  similar  experience 
with  others  among  the  introduced  insects  had  indicated  that  larger 
colonies  were  likely  to  be  required,  it  was  determined  to  liberate  all 
the  adult  Calosomas  in  one  locality  as  they  were  received  from  abroad, 
and  thus  secure  its  establishment,  if  this  were  possible,  before  attempt- 
ing furl  her  artificial  dispersion.  This  was  done,  and  several  hundred 
had  been  received  and  thus  liberated  by  the  time  Mr.  Burgess  was 
ready  to  take  full  charge  of  the  work. 

Although  it  was  quite  late  in  the  season,  Mr.  Burgess,  with  the 
assistance  of  Mr.  C.  W.  Collins,  who  lias  remained  associated  with 
him  ever  since,  succeeded  in  securing  the  eggs  and  in  carrying  to 
maturity  several  larvae  of  the  species  in  close  confinement  in  jars  of 


PARASITES  OF  GIPSY-MOTH  PUP.E. 


255 


earth,  and  effectually  demonstrated  the  superiority  of  this  method 
over  t hut  involving  the  use  of  the  large  out-of-door  cages.  The  fol- 
lowing spring  the  work  was  undertaken  upon  a  considerably  larger 
scale,  and  along  still  more  specially  developed  lines.  From  the 
hibernated  parent  stock,  and  from  newly  imported  beetles,  he  reared 
large  numbers  of  larva',  a  part  of  which  were  allowed  to  complete 
their  transformations  in  confinement,  while  others  were  colonized 
directly  in  the  open  when  about  half  grown.  These  larval  colonies 
promised  to  be  successful,  and  accordingly  the  work  of  rearing  the 
lar\ie  and  distributing  them  throughout  the  gipsy-inoth-infested  area 
in  eastern  Massachusetts,  with  an  occasional  incursion  into  other 
parts  of  the  infested  area,  was  continued  throughout  11)09  and  1910. 

Meanwhile,  beginning  in  the  late  summer  of  1907  and  continuing 
uninterruptedly  until  the  close  of  the  season  of  1(.)1(),  Caloeoma  has 
been  steadily  gaining  in  the  Confidence  of  those  who  have  watched 
its  progress.  Its  larvae  were  first  recovered  from  the  field  at  just 
about  the  time  when  Mr.  Burgess  first  took  over  the  beetle  work,  and 
its  ability  to  complete  its  seasonal  cycle  in  America  unassisted  was 
thus  indicated.    The  large  colony  was  also  proved  to  be  unnecessary. 

Its  progress  ill  the  field  was  slow  at  first,  even  in  the  instance  of 
the  large  adult  colony  founded  in  19(>7  before  it  was  known  to  have 
become  established.  In  1008  its  larvae  were  found  in  abundance  in 
the  center  of  this  colony,  but  not  to  any  great  distance  away  from 
the  point  where  the  beetles  had  first  been  liberated.  In  1909  the 
Spread  was  more  rapid,  but  at  the  same  time  restricted  in  comparison 
with  t  hat  which  became  evident  in  1910.  As  will  be  seen  by  reference 
to  the  accompanying  map  (PL  KXXV)  which  has  been  prepared  by 

Mr.  Burgess  From  the  results  of  the  scouting  work  of  three  years,  its 
apparent  or  discernible  dispersion  has  been  at  a  rapidly  increasing 
rate  each  year  in  the  instance  of  colonies  which,  like  these,  chanced 
to  be  so  happily  located  as  to  allow  for  unrestricted  and  uninter- 
rupted increase  from  t  he  st  art. 

At  th>  present  time  there  is  every  prospect  that  a  continued  rapid 
increase  for  a  few  years  more  will  result  in  an  abundance  of  the 
beetles  sufficient  to  render  very  eflicient  aid  in  the  fight  against  the 
moth.  It  is  not  expected  that  they  will  be  of  very  much  assistance 
in  localities  in  which  the  moth  is  reduced  to  such  numbers  as  to  make 
control  through  parasites  such  as  Compsilura  and  others  of  its  char- 
acter possible,  but  it  is  expected  that  whenever  the  moth  breaks  out 
of  bounds,  and  increases  to  such  abundance  as  to  afford  the  beetles 
and  their  larvae  an  unlimited  food  supply,  first  migration  and  later 
rapid  multiplication  of  the  beetle  will  result.  In  this  respect  the 
role  played  byCalosoma  is  similar  to  thai  which  is  rather  confidently 
expected  of  Blepharipa. 


256 


PARASITES  OF  GIPSY  AND  BROWN -TAIL  MOTHS. 


THE  EG(x  PARASITES  OF  THE  BROWN-TAIL  MOTH. 


THE  GENUS  TRICHOGRAMMA. 


The  parasites  belonging  to  the  genus  Trichogramma,  of  which  sev- 
eral have  been  reared  from  eggs  of  the  brown-tail  moth,  are* the  most 
minute  of  any  which  have  been  handled  at  the  laboratory,  and  are 
among  the  smallest  of  insects.  The  egg  of  the  brown-tail  moth  is  in 
form  of  a  flattened  spheroid,  approximately  as  large  in  its  greatest 
diameter  as  the  printed  period  which  ends  this  sentence.  Normally 
two  or  three  individuals  of  the  parasite  pass  through  all  of  their 
transformations  from  egg  to  adult  upon  the  substance  of  a  single 
host  egg,  and  in  exceptional  instances  as  many  as  10  perfect  adults 
are  known  to  have  issued  from  one  egg.  This  is  the  more  remarkable 
when  it  is  remembered  that  the  female  Trichogramma  is  sexually 
mature  at  the  time  of  issuance,  and  ready  to 
deposit  a  large  number  of  eggs  for  a  new 
generation. 

The  mother  parasite  exhibits  little  discretion 
in  the  selection  of  host  eggs  for  attack  (fig.  57), 
and  if  any  dependence  is  to  be  placed  upon 
observations  which  have  been  made  in  the 
laboratory,  she  is  quite  as  likely  to  select  eggs 
which  contain  caterpillars  nearly  ready  to 
hatch  as  those  which  are  freshly  deposited. 
The  feeding  habits  of  her  young  are  such  as  to 
permit  a  considerable  latitude  in  tins  respect, 
but  there  is  a  certain  limit,  and  after  the  em- 
bryological  development  has  passed  beyond  a 
certain  point  in  the  host  egg,  the  attack  by  the 
parasite  is  unsuccessful.  It  is  much  better 
that  the  host  egg  be  dead  than  that  it  contain  a  living  embryo  in  the 
later  stages  of  its  development. 

The  life  cycle,  from  egg  to  adult,  varies  very  considerably  in 
length  in  accordance  with  the  prevailing  temperature.  In  the  summer 
it  may  be  completed  in  as  short  a  period  as  nine  days,  while  in  the 
fall  three  weeks  or  more  may  be  required.  If  the  temperature  falls 
below  certain  limits  the  young  parasites  will  hibernate  or  attempt 
to  hibernate,  and  thereafter  their  development  may  be  delayed  for 
several  weeks,  or  even  months,  even  though  they  are  exposed  to 
continuous  high  temperature  during  this  period. 

After  about  one-third  of  the  time  requisite  for  the  completion  of 
the  life  cycle  has  elapsed,  the  eggs  begin  to  turn  dark,  and  finally 
become  -Inning,  lustrous  black  (fig.  58).  This  change  is  brought 
about  by  the  preparation  of  .the  larva?  for  pupation. 


Fig.  57. — Trichogramma  sp.  in 
act  of  oviposition  in  an  egg  of 
the  brown-tail  moth.  Great- 
ly enlarged.  (Original.) 


EGG  PARASITES  OF  THE  BROWN -TAIL  MOTH. 


257 


Three  races  or  species  have  been  reared  from  the  eggs  of  the  brown- 
tail  mot h ,  two  of  them  being  European  and  the  third  American. 
The  American,  according  to  Mr.  A.  A.  Girault,  to  whom  the  series  of 
mounted  individuals  was  submitted  for  determination,  is  the  com- 
mon and  widely  distributed  Trichogramma  pretiosa  Riley.  One  of  the 
European,  which  is  here  referred  to  as  the  pretiosa-likc  form,  is  or 
appears  to  be  structurally  identical  with  the  American  pretiosa.  It 
differs  in  that  the  progeny  of  parthenogenetic  or  unfertilized  females 
is  either  of  both  sexes,  or  else  exclusively  female,  while  the  progeny 
of  unfertilized  females  of  the  Americas  species  baa  always  been 
exclusively  male  in  the  very  considerable  number  of  reproduction 
experiments  with  such  females  which  have  been  carried  on  at  the 
laboratory  . 

The  other  European  species  may  at  once  be  distinguished  from  either 
of  its  congeners  by  its  dark  color,  as  well  as  by  other  characters  of 
taxononiic  value.  Like  the  American  race  of  T.  j>r<  tinsa  which  was 
studied  at  the  laboratory,  it  produced  males  exclusively  as  the 
result  of  parthenogenetic  re- 
production.  _  /  y  - .  . 

1 1  seems  to  t he  w  liter  that 
in  the  two  morphologically 
identical  but  biologically  dis- 
tinct   races  oi   '1  richogra  mma     rm.U    Eggs  of  the  brown-tall  moth,  ft  portion  of 

(  7     luiliosd     American  Or   Kll-        which  has  Imvii  jiura-sitizt'd   l>y  Trichogramma  sp. 

1  I  '    .        Ll  Original 

ro|)ean)  w  e  have  w  hat  is  not  h- 

ing  Less  than  two  species,  quite  as  distinct  as  are  the  species  of 

bacteria,  for  example,  which  are  founded  upon  cultural  characters. 
If  the  manner  in  which  a  bacterium  reads  when  cultivated  upon 
a  certain  medium  prepared  after  a  fixed  formula  may  be  considered 
as  sufficient  to  separate  it  specifically  from  an  otherwise  indis- 
tinguishable form  which  reacts  in  a  different  manner  under  identical 
circumstances,  why  may  not  the  same  distinctions  be  made  to  apply 
to  insects'  It  may  not  appeal  to  the  taxonomisl  and  student  in 
comparative  insect  morphology,  but  it  certainly  will  appeal  to  the 
economic  entomologist,  who  has,  or  ought  to  have,  a  greater  interest 
in  the  biological  than  in  the  anatomical  characteristics  of  the  subjects 
of  his  investigations.  The  case  of  Trichogramma  is  by  no  means 
unique.  That  of  Tachina  mella,  which  is  practically  indistinguishable 
from  T.  larvarum  but  which  reacts  differently  in  its  association  with 
the  gipsy  moth,  is  another.  Another  is  to  be  found  in  the  American 
and  European  races  of  Parexorista  chelonix.  There  are  also  others, 
which  need  not  be  mentioned  here,  but  which  will  receive  attention, 
it  is  hoped  and  intended,  at  some  future  time. 

These  statements  concerning  the  behavior  of  the  several  forms  of 
Bpecies  of  the  genus  Trichogramma  are  based  upon  the  results  of 
95677°— Baa  1)1— n  17 


258  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

something  like  275  separate  but  similar  experiments  in  their  repro- 
duction in  confinement  in  the  laboratory.  It  is  of  course  possible, 
since  it  was  especially  desired  to  continue  the  experiments  as  long 
as  possible  with  individuals  of  known  parentage,  that  the  results  are 
misleading.  Possibly  had  American  Trichogramma  been  collected 
in  the  open  from  a  variety  of  sources,  a  race  might  have  been  found 
which  was  arrhenotokous,  even  as  the  similar  search  might  have 
resulted  in  the  discovery  of  a  thelyotokous  race  in  Europe.  As  it 
is,  the  American  stock  was  once  renewed.  In  1907  a  series  of  experi- 
ments was  conducted  with  parent  stock  reared  from  brown-tail  moth 
eggs  collected  in  Maine,  and  in  1908  a  similar  but  more  extensive 
series  with  parent  stock  from  eggs  of  the  brown-tail  moth  collected 
in  Massachusetts.    In  each  instance  the  results  were  the  same. 

The  longest  series  of  experiments  with  the  arrhenotokous  Euro- 
pean race  was  with  the  progeny  of  individuals  reared  from  one  lot 
of  European  eggs  from  the  Province  of  Carniola,  Austria.  Similar 
experiments  with  one  other  lot  of  females  upon  another  shipment 
of  eggs  from  the  same  Austrian  province  and  perhaps  from  the  same 
locality  resulted  similarly,  but  the  series  was  not  nearly  so  long.  In 
the  first-mentioned  series  13  generations  were  reared  in  the  laboratory, 
all  but  the  first  three  being  parthenogenetic.  Males  were  secured 
at  one  time,  and  for  a  limited  number  of  generations,  but  soon  dis- 
appeared, even  from  the  progeny  of  mated  females.  The  results 
of  these  experiments  will  be  published  in  detail  later. 

Importations  of  egg  masses  of  the  brown-tail  moth  which  had  been 
collected  in  the  open  in  Europe  were  first  attempted  in  the  summer  of 
1906,  and  from  almost  the  first  of  those  which  were  received  at  the 
laboratory  a  few  examples  of  the  pretiosa-like  European  form  were 
reared.  Mr.  Titus  attempted  to  secure  reproduction  in  the  labora- 
tory that  first  season,  but  as  he  had  no  supply  of  host  eggs  in  which 
embryonic  development  was  not  considerably  advanced,  his  attempts 
met  with  failure. 

In  1908  a  larger  number  of  egg  masses  of  the  brown-tail  moth  was 
imported  from  a  great  variety  of  European  localities,  and  as  before, 
the  p?netiosa-\ike  Trichogramma  was  quickly  secured.  The  failure 
of  the  previous  season  and  its  cause  had  early  been  taken  into  ac- 
count, and  some  time  before  a  large  quantity  of  fresh  eggs  of  the 
brown-tail  moth  had  been  collected  and  stored  at  a  temperature 
sufficiently  low  to  prevent  embryological  development.  When  sup- 
plied with  a  quantity  of  these  eggs  the  imported  Trichogramma  ovi- 
posited with  the  greatest  freedom,  and  in  the  course  of  a  few  genera- 
tions had  increased  enormously,  so  that  many  thousands  were  lib- 
erated later  in  the  fall.  It  was  conclusively  demonstrated  that 
even  though  the  host  eggs  were  dead,  abundant  reproduction  could 
he  easily  obtained  under  laboratory  conditions. 


EGG  PARASITES  OF  THE  BROWN -TAIL  MOTH. 


259 


A  large  number  of  parasitized  eggs,  containing  t lie  brood  in  various 
stages  of  development,  were  placed  in  cold  storage  and  kept  until 
the  following  June  and  July.  when,  upon  being  removed,  a  few  of 
the  parasites  completed  their  transformations.  With  these  as  pa- 
rents large  numbers  were  reared  in  the  laboratory  upon  the  fresh 
eggs  of  the  brown-tail  moth,  at  that  time  abundantly  available,  and 
the  cold-storage  experiment  was  repeated  during  the  winter  of  1908-9 
with  much  better  results  than  before.  An  abundant  supply  of  parent 
females  was  available  in  the  summer  of  1 909,  and  a  great  many 
thousands  of  the  parasite  were  reared  and  liberated  under  the  most 
favorable  conditions  which  could  possibly  be  desired  or  devised. 
Many  thousands  were  known  to  have  issued  from  parasitized  eggs 
contained  in  small  receptacles  attached  to  the  branches  of  the  trees 
upon  which  the  brown-tail  moths  were  even  then  depositing  eggs 
in  abundance. 

No  false  hopes  were  felt  as  to  the  probable  success  of  this  venture. 
It  has  been  amply  demonstrated  in  the  Laboratory  that  the  females 
were  unable  to  penetrate  the  egg  mass  for  the  purpose  of  oviposition, 
and  the  location  in  the  mass  of  the  few  eggs  parasitized  by  the 
American  race  of  preUo80  indicated  sufficiently  well  the  inability  of 
that  species  to  do  better  in  the  open  than  cither  it  or  the  European 

would  do  in  confinement. 

Accordingly  no  disappointment  was  felt,  when  it  was  found  that 
the  degree  <>f  parasitism  effected  by  the  European  species  in  the 

immediate  vicinity  of  the  colony  Bites  w  as  hardly,  if  any.  greater  than 

that  ordinarily  effected  by  the  native  species.  It  is  hardly  a  physical 
possibility  for Trichogramma  to  effect  more  than  a  small  percentage 

of  parasitism  in  the  egg  mass  of  the  brown-tail  moth,  and  the  value 
of  the  genus  as  represented  by  the  three  species  or  forms  which  have 
been  studied  at  the  laboratory  slight. 

At  the  same  time,  it  is  not  felt  that  the  labor  which  has  been 
expended  in  an  attempt  to  give  Trichogramma  a  fair  test  has  been 
altogether  lost.  There  are  numerous  other  hosts  upon  which  it  is 
a  very  ellicient  parasite,  and  it  is  easily  conceivable  that  at  some 
future  time  it  will  be  found  possible  to  utilize  it  in  some  manner 
which  the  circumstances  themselves  will  suggest. 

As  a  possible  example  may  be  mentioned  the  tortricid  Archips 
rosaceana  Harris,  which  at  times  becomes  a  pest  in  greenhouses 
devoted  to  the  growing  of  roses.  In  Volume  II,  No.  6,  of  the  Journal 
of  Economic  Entomology,  Prof.  E.  I).  Sanderson  describes  such  an 
outbreak  in  a  large  rose  house  in  New  Hampshire  under  the  heading 
of  <k  Parasites."    Prof.  Sanderson  says: 

The  out  break  observed  by  as  furnished  a  case  of  the  most  complete  parasitism  we 
have  ever  seen.  W  hen  first  observed,  in  late  July,  from  one-third  to  one-half  of  the 
eggB  were  parasitized  by  a  species  of  Trichotxramma.    Two  weeks  later  it  was  difficult 


260  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

to  find  an  egg  mass  in  which  over  95  per  cent  of  the  eggs  did  not  contain  the  black 
pup.c  of  the  parasite  and  in  most  cases  99  to  100  per  cent  were  affected.  So  effective 
were  the  parasites  that  the  control  of  the  outbreak  was  undoubtedly  due  to  them  much 
more  than  to  any  remedial  measures. 

At  about  the  time  when  the  American  parasite  was  reaching  a  state 
of  efficiency,  a  large  number  of  eggs  of  the  brown-tail  moth  contain- 
ing the  brood  of  one  of  the  European  species  was  sent  to  Prof.  Sander- 
son for  liberation  in  the  rose  house.  They  were  received  too  late  for 
service,  but  had  they  been  sent  at  an  earlier  date  it  might  easily  have 
been  claimed,  and  with  perfect  confidence,  that  the  final  results  were 
the  direct  outcome  of  the  colonization  experiment. 

In  such  circumstances  as  these  it  would  (or  at  least  it  seems  from 
this  distance  as  though  it  would)  easily  be  possible  and  practicable 
to  collect  masses  of  the  parasitized  eggs  and  by  keeping  them  in  cold 
storage  have  ready  at  hand  within  the  following  twelvemonth  a 
supply  of  the  parasites  which  would  be  available  should  the  natural 
stock  perish  through  lack  of  food,  and  the  destructive  increase  of  the 
host  follow.  Parasitized  eggs  could  be  sent  from  one  greenhouse  to 
another,  and  stock  could  be  kept  in  cold  storage  in  one  city  to  be 
drawn  upon  by  a  florist  in  any  other  part  of  the  country  when  need 
arose. 

Another  possible  use  for  the  parasite  is  as  an  enemy  of  Heliothis, 
which  is  causing  serious  injury  to  tobacco  in  Sumatra.  Dr.  L.  P. 
De  Bussy,  biologist  of  the  tobacco  growers'  experiment  station  at 
Deli,  has  already  undertaken  its  introduction  there,  and  will  attempt 
to  handle  it  after  somewhat  the  same  manner  as  that  above  described. 

TELENOMUS  PH  ALJE N ARUM  NEES. 

A  small  number  of  this  species  was  reared  from  imported  eggs  of 
the  brown-tail  moth  from  several  European  localities  in  1906,  and  an 
attempt  was  made  to  secure  reproduction  in  the  laboratory.  Ovi- 
position  was  secured,  as  in  the  instance  of  similar  attempts  with 
Trichogramma,  but  it  did  not  result  successfully,  and  apparently  for 
the  same  reason. 

In  1907  a  somewhat  larger  number  was  reared,  and  an  abundant 
supply  of  suitable  host  eggs  having  been  provided,  this  number  was 
soon  increased  several  fold,  and  one  large,  and  several  smaller  colonies 
of  the  parasite  were  liberated  under  very  satisfactory  conditions  late 
in  the  summer.  It  was  found  that  the  reproduction  could  be  secured 
upon  host  eggs  which  had  been  killed  through  exposure  to  cold,  and 
the  experiment  was  made  of  hibernating  the  brood  in  cold  storage, 
but  without  success. 

In  L908  the  quantity  of  eggs  of  the  brown-tail  moth  imported  was 
smaller  than  during  the  previous  year,  and  only  a  very  small  propor- 
tion of  them  proved  to  be  attacked  by  the  Telcnomus.    Not  nearly 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS. 


261 


enough  for  a  satisfactory  colony  were  reared,  and  again  it  was  at- 
tempted to  hold  the  brood  over  winter  in  cold  storage,  and  again  the 
attempts  failed. 

If  judgment  is  based  upon  the  percentage  of  parasitism  by  this 
species  in  the  lots  of  egg  masses  of  the  brown-tail  moth  which  have 
been  received  from  abroad,  it  is  an  unimportant  parasite  in  Europe. 
Partly  on  this  account,  and  more,  perhaps,  because  it  was  colonized 
so  satisfactorily  in  1907,  no  further  attempts  to  secure  its  hit  rod  net  ion 
into  America  have  been  made.  Neither  has  a  serious  attempt  to 
recover  it  from  the  field  in  the  vicinity  of  the  1907  colony  site  been 
made,  and  it  may  have  become  established  from  this  colony. 

The  plana  for  held  work  in  1911  include  the  collection  of  a  Large 
number  of  eggs  of  the  brown-tail  moth  from  the  general  vicinity  of 
the  larger  colonies  of  1907  and.  it'  arrangements  can  be  perfected,  for 
a  study  of  the  extent  to  which  the  eggs  of  the  brown-tail  moth  are 
attacked  by  parasites  in  Kuropc.    As  in  the  caae  of  every  other  cla^s 

of  parasite  material  received  at  the  laboratory,  nothing  ia  known  of 
the  circumstance^  under  which  those  egg  masses  which  were  received 

from  1906  to  1908  Were  collected.     It  may  easily  be  that  they  were 

collected  too  soon  following  their  deposition  to  permit  of  their  having 
been  parasitized  to  anything  like  the  extent  which  would  have  come 
about  had  they  been  allowed  to  remain  in  the  open  For  a  few  days 
longer,  and  in  at  least  one  instance  the  receipt  of  the  masses  with  a 
dead  female  moth  accompanying  each  was  suilieient  to  more  than 
justify  such  doubts. 

PARASITES    WHICH    HIBERNATE    WITHIN    THE    WEBS    OF  THE 

BROWN-TAIL  MOTH. 

Partly  because  it  has  been  practicable  to  import  the  gipsy  moth 
and  the  brown-tail  moth  in  the  hibernating  state  in  better  condition 
than  it  has  been  possible  to  import  their  active  summer  stages,  but 
equally  because  there  has  been  ample  time  and  opportunity  to  study 
them  during  the  winter  months  when  only  a  limited  amount  of  held 
work  could  be  done,  it  has  been  possible  to  learn  more  of  the  parasites 
which  hibernate  within  the  gipsy-moth  eggs  and  the  nests  of  the 
brown-tail  moth  than  of  those  parasites  which  are  only  associated 
with  the  same  hosts  during  a  more  or  less  limited  time  in  the  summer. 
The  winter  nests  of  the  brown-tail  moth  have  from  the  beginning 
been  the  subject  of  an  increasingly  intensive  study,  and  as  a  result 
more  is  known  of  the  parasites  which  hibernate  within  them  than  of 
any  other  group  of  brown-tail  moth  or  the  gipsy-moth  parasites  with- 
out excepting  even  the  parasites  of  the  gipsy-moth  eggs. 

Very  large  numbers  of  these  nests,  amounting  in  the  aggregate  to 
more  than  300,000,  have  been  imported  each  winter  from  that  of 
1905-6  to  that  of  1909-10,  inclusive,    Now  that  all  of  the  primary 


262 


PARASITES  OF  GTPSY  AND  BROWN-TAIL  MOTHS. 


parasites  known  to  hibernate  within  them  are  believed  to  be  thor- 
oughly well-established  in  America,  their  importation  has  been  dis- 
continued. 

These  parasites,  including  two  which  are  secondary,  number  eight 
species  in  all,  and  will  be  first  considered  as  a  group.  In  the  subse- 
quent pages  each  will  be  taken  up  separately,  and  the  story  of  its 
importation  and  progress  in  America  will  be  told.  The  species  are  as 
follows : 

Monodontomerus  sevens  Walk.  Adult  females  hibernate  within 
the  nests,  but  do  not  attack  the  caterpillars. 

Pteromalus  egregius  Forst.  Females  enter  the  nest  in  the  fall 
and  oviposit  upon  the  caterpillars  after  they  have  become  dormant. 
Their  eggs  are  deposited,  and  the  larvae  feed  externally  (fig.  59),  be- 
coming full  fed  before  cold  weather  puts  a  stop  to  their  activity. 
Transformations  are  completed  in  the  spring,  and  adults  of  the  new 
generation  leave  the  nosts  about  two  or  three  weeks  following  resump- 
tion of  activity  on  the 
part  of  the  caterpillars. 

Apanteles  lacteicolor 
Vier.  Attack  is  presum- 
ably made  upon  the  very 
small  active  caterpillars 
in  the  fall  before  they 
enter  the  nests  for  the 
winter.  The  parasitized 
caterpillars  hibernate 
and  resume  activity  in 
the  spring.  About  the 
time  when,  had  they  re- 
mained health}",  they 
would  have  molted  for 
the  first  time,  they  die, 
and  the  parasite  larva  soon  issues  and  spins  a  white  cocoon  within 
the  molting  web,  which  may  or  may  not  be  upon  the  winter  nests. 
There  is  no  second  generation  upon  the  caterpillars  of  the  brown- 
tail  moth  the  same  season. 

Meteorus  versicolor  Wesm.  Habits  essentially  the  same  as  those 
of  Apanteles  until  after  the  caterpillars  have  resumed  activity  in  the 
spring.  The  parasitized  individuals  usually  live  to  molt  once,  and 
are  overcome  and  destroyed  away  from  the  molting  web  or  nests. 
The  cocoons,  which  are  characteristic  of  the  genus,  swing  from  the 
end  of  long  threads.  The  adults  issuing  from  them  immediately 
attack  the  larger  caterpillars  of  the  brown-tail  moth  for  a  second 
generation. 

Zygobotkria  nidicola  Towns.  Hibernating  habits  similar  to  those 
of  Apanteles  and  Meteorus.  The"  affected  caterpillars  become  full 
grown  and  spin  for  pupation  before  being  overcome  by  their  parasite. 
Sometimes  they  pupate.  The  parasite  adult  issues  at  about  the  time 
when  the  moth  would  have  issued  had  the  caterpillar  completed  its 
t  ransformat  ions.  There  is  but  one  generation  annually,  and  no  alter- 
nate host  is  necessary. 


Fig.  59.— Larvae  of  Pteromalus  egregius  feeding  on  hibernating 
caterpillars  of  the  brown-tail  moth.  Much  enlarged.  (Origi- 
nal.) 


IWRASTTES   HIBERNATING  IN  BROWN-TAIL  WEBS. 


263 


Cotnpsilunt  conrinnata  Meig.  Hibernating  larva4  are  occasionally 
^und,  but  apparently  do  not  complete  their  transformations  in  the 
spring. 

Mesochorus  paUipes  Brischke.  Occasionally  reared  as  a  parasite 
of  A  pa  ntdes  lacteicolor.  The  Ap  an  teles  larva  reaches  full  maturity  and 
spins  its  cocoon,  but  is  overcome  before  pupating.  The  Mesochorus 
adult  issues  from  the  cocoon  a  very  few  days  later  than  would  the 
Apanteles  had  it  remained  alive. 

Entedon  aJMtarsis  AshuL  An  internal  parasite  within  the  larvae  of 
Pteromalus  egregius. 

The  appearance  of  the  hibernating  Larvae  of  the  Pteromalus  is  indi- 


1 


Fig.  00. —  Port  ion  of  brown-tail  moth  IMtta,  torn  open,  riwwlug  caterpillars 
attacked  by  larva- of  Vt>  romnlus  cyrci/ius.    Knlarged.  (Original.) 

Oated  fairly  well  in  the  accompanying  illustration  (fig.  GO),  which 
represents  i\  "  pocket  "of  |>arasili/ed  <-:i  1  erpillars  torn  open.  Very  little 
of  interest  is  associated  with  the  life  and  feeding  habits  of  these  larva?. 
The  female  pierces  the  host  caterpillar  with  her  ovipositor  preliminary 
to  the  deposition  of  her  egg  externally, 
and  the  caterpillar  thus  stum:  is  fre- 
quently rendered  quiescent,  and  may 
even  die  before  the  hatching  of  the  para- 
site larva*. 

The  hibernating  larva  of  Apanteles  is 
so  small  as  to  be  very  difficult  of  detec- 
tion until  after  it  has  resumed  activity 
in  the  spring  and  increased  in  size.  Its 
exact  appearance  during  the  hibernating  stage  can  not  be  de- 
scribed, because  nearly  every  specimen  found  has  been  injured 
more  or  less  in  the  removal.  The  accompanying  illustration 
(fig.  61)  is  from  a  sketch  made  by  Mr.  Timberlake  of  a  half-grown 
Larva  from  life.  None  of  the  preserved  specimens  shows  the  curious 
projection  beneath  the  anal  bladderlike  appendage  which  latter  is 
characteristic  of  the  early  stage  larvae  of  the  subfamily  to  which 
Apanteles  belongs.    The  head  and  mouthparts  are  strikingly  dis- 


Fig.  61.— A pantdts  lacteicolor:  Imma 
ture  larva  from  hibernating  caterpillar 
of  ilif  DXOwn-taO  moth.  Much  en- 
larged. (Original.) 


264 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


similar  from  those  of  the  first-stage  Meteorus,  and  are  so  little  differ- 
entiated as  to  be  indescribable. 

The  hibernating  stage  of  Meteorus  is  in  remarkable  contrast  to 
that  of  Apanteles.  The  accompanying  drawing  (fig.  62)  is  from  a 
balsam  mount,  and  represents  an  individual  which  has  resumed  activ- 
ity and  grown  very  slightly  larger  and  plumper  than  is  character- 


FlG.  62. — Meteorus  versicolor:  Immature  larva  from  hibernating  caterpillar  of  the 
brown-tail  moth.    Much  enlarged.  (Original.) 

istic  of  its  hibernating  condition.  These  larvae  are  curiously  anoma- 
lous, in  that  though  they  are  actually  first-stage,  the  head  alone  is 
considerably  larger  than  the  original  egg  as  deposited  by  the  mother. 

An  interesting  series  of  dissections  made  by  Mr. 
Timberlake  in  the  spring  of  1910  served  to  ex- 
plain this  apparent  anomaly.  The  eggs  are  very 
small  when  first  deposited  and  almost  globular. 
Apparently  with  the  beginning  of  embryological 
development  they  begin  to  grow  and  by  the  time 
the  inclosed  embryo  begins  to  assume  the  charac- 
teristics of  the  larva  they  have  reached  a  diame- 
ter at  least  four  times  greater  than  that  of  the 
newly  deposited  egg.  The  enormous  chitinized 
head,  with  strong,  curved  mandibles,  is  in  strange 
contrast  to  the  undifferentiated  cephalic  segment 
of  Apanteles  and  is  apparently  closely  analogous 
to  the  large-headed,  heavily  mandibled  larvae  of 
the  Platygasters,  as  described  by  Ganin,  March al, 
and  others.  There  are  many  points  of  resemblance 
between  the  two  forms,  and  it  would  seem,  without 
going  into  the  matter  at  all  deeply,  as  though  the 
type  of  embryological  and  early  larval  development 
characteristic  of  Meteorus  were  essentially  the  same 
as  that  of  the  Platygasters  and  many  ichneumonid 
genera,  while  that  of  Apanteles  would  have  to  be 
considered  as  of  an  essentially  different  tjTpe. 

In  both  Apanteles  and  Meteorus  the  later  larval  stages  are  much 
more  conventionalized  and  more  like  the  familiar  type. 

The  position  assumed  by  the  Apanteles  larva  is  not  very  definitely 
known.    The  Meteorus  larva  usually  lies  superior  to  the  alimentary 


Fig.  Cfi.—Zygobothria  vi- 
dicola:  First-stage  larvae 
in  situ  in  walls  of  crop  of 
hibernating  brown-tail 
moth  caterpillar.  Great- 
ly enlarged.  (Original.) 


PARASITKS   HIHKKXATIXO  IN   BROWN -TAIL  WEBS. 


265 


canal,  its  axis  parallel  to  the  axis  of  the  body  of  the  host  caterpillar, 
and  its  head  in  the  ultimate  or  penultimate  body  segment,  and 
pointed  toward  the  rear. 

The  larvoe  of  Zygobothria  are  similarly  assumed  to  a  definite 
petition,  and  in  otherwise  healthy  caterpillars  have  invariably  been 
found  embedded  in  the  walls  of  the  crop,  as  indicated  by  figure  63. 
lu  appearance  they  are  typical  of  the  tachinid  first-stage  larva?  gen- 
erally, and  with  DO  extraordinary  points  of  difference  from  most 
others  of  the  group  to  which  they  belong.  Those  of  Compsilura 
(fig.  64)  may  be  found  in  similar  positions,  but  they  are  easily  dis- 
tinguishable from  Zygobothria  by  the  presence  of  the  three  chitinous 
anal  hooks  or  spines,  as  indicated  in  the  accompanying  figure. 

Nothing  is  known  of  the  hibernating  stage  of  Mesochorus.     It  does 

not  seem  probable  thai  it  should  resemble  the  planidium  of  Perilam- 

pus.  which,  like   Mesochorus.  is  a  secondary  parasite  which  gains 
access  to  its  host  before  (he  latter  has  left  the  body  of  the  caterpillar 
which  harbors  both  primary  and  secondary.     It  is 
presumed  that  it  w  ill  be  representative  of  a  highly 

specialized  type  of  development  which  fits  it  for 
the  peculiar  role  which  it  plays,  hut  that  this  de- 
velopment will  have  been  along  wholly  different 
lines  from  thai  which  has  taken  place  in  the  Case 
of  Perilampus.  The  w  hole  genus,  apparent  ly.  pos- 
sesses habits  similar  to  t  hose  of  1A  sochorus  pnll'iju  s. 
A  very  beautiful  and.  according  to  Mr.  Yiereck,  an 
undescribed  species  has  been  reared  from  the 
COCOOnS  of  A  pantries  fiskci,  parasitic  upon  a  species 

of  Parorgyia,  under  circumstances  which  indicate 

positively  that  attack  was  made  while  the  pri- 
mary host  was  still  alive.  The  same  may  be  said 
of  another  undetermined  species  which  has  simi- 
larly been  reared  from  Apanteles  hyphantrix. 

Mesochorus  paUipes  is  not  an  uncommon  parasite  of  Apanteles 
lacieicolor  Vier.,  having  been  reared  from  only  a  few  among  the  many 

localities  from  which  its  host  has  been  secured  in  numbers,  but  the 
average  proportion  of  parasitized  individuals  has  been  only  about 
2  per  cent. 

The  interrelations  of  these  several  parasites  thus  closely  associated 
with  one  stage  of  the  same  host,  and  consequently  with  each  other, 
are  interesting  and  peculiar.  Pteromalus,  of  course,  cares  little 
whether  the  host  caterpillar  selected  for  attack  is  parasitized  by 
one  or  more  of  the  endoparasites  which  hibernate  as  first-stage  larvae. 
The  female  will  undoubtedly  attack  parasitized  as  freely  as  it  will 


Fig.  (A.— Compsilura  con- 
cinnata:  First-stage  lar- 
va. Oreatly  enlarged. 
(Original.) 


266 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


attack  unparasitized  caterpillars  and  its  larvae  develop  as  satisfac- 
torily upon  the  one  as  upon  the  other,  and  at  the  expense  of  the 
other  internal  parasites  as  well  as  of  the  primary  host.  But  the 
matter  does  not  stop  here.  The  adults  issue  from  the  hibernating 
nests  at  just  about  the  time  when  the  Apanteles  are  issuing  from  the 
young  caterpillars  and  spinning  their  cocoons  in  the  molting  webs, 
which  are  very  frequently  in  the  outer  interstices  of  the  very  same 
nests  from  which  the  Pteromalus  are  also  issuing.  The  females  of 
the  latter  are  ready  to  oviposit  almost  immediately  following  their 
eclosion,  and  will  oviposit  with  the  greatest  freedom  in  the  cocoons 
of  Apanteles  or  of  Meteorus  whenever  they  chance  to  encounter 
them.  Thus  it  comes  about  that  the  Pteromalus,  after  passing  one 
generation  as  a  primary  parasite  of  the  brown-tail  moth,  immediately 
passes  another  as  a  secondary  upon  the  same  host.  Undoubtedly  it 
would  thrive  equally  as  well  upon  Mesochorus  as  upon  Apanteles. 
Proof  of  this  could  unquestionably  be  secured  through  the  careful 
dissection  of  the  very  large  number  of  cocoons  from  which  it  had 
issued  in  the  laboratory,  some  of  which,  it  is  certain,  must  have  con- 
tained Mesochorus  as  well,  but  proof  is  realty  unnecessary.  By 
doing  so,  it  becomes  tertiary  upon  the  same  host  as  that  upon  which 
it  is  habitually  and  regularly  a  primary  and  secondary  parasite. 

Entedon,  were  it  to  follow  Pteromalus  through  its  varied  adventures, 
would  in  like  manner  (as  it  probably  does)  become  successively  sec- 
ondary, tertiary,  and  quaternary. 

Monodontomerus,  commonly  a  primary  parasite  upon  the  pupa  of 
the  brown-tail  moth  or  gipsy  moth  and  only  present  as  a  regular 
guest  in  the  winter  nests,  is  none  the  less  pretty  intimately  connected 
with  them  in  other  ways.  It  directly  attacks  the  cocoons  of  the 
Apanteles,  acting  in  all  respects  like  a  secondary  parasite,  and  thereby 
comes  into  direct  conflict  with  Pteromalus,  one  of  the  other  of  which 
must  develop  at  the  expense  of  its  competitor.  It  also  will  become 
tertiary  whenever  it  chances  to  attack  a  cocoon  containing  Meso- 
chorus as  a  secondary  parasite  on  Apanteles.  It  is  also  a  parasite  of 
tachinid  puparia,  and  especially  of  tachinid  puparia  which  it  encoun- 
ters associated  with  the  gipsy  moth,  or  the  brown-tail  moth,  and 
thereby  becomes  a  parasite  of  Zygobothria  and  in  consequence  a 
secondary  parasite  of  the  brown-tail  moth. 

Should  Apanteles  and  Meteorus,  or  Apanteles  and  Zygobothria 
chance  to  become  located  in  the  same  host,  the  Apanteles,  because 
of  its  more  rapid  development  in  the  spring,  would  certainly  be  the 
winner. 

When  Meteorus  and  Zygobothria  enter  into  competition  for  pos- 
session of  the  same  host  individual,  Meteorus  is  invariably  the  win- 
ner and  is  in  no  way  affected  by  the  presence  of  the  other  parasite. 
In  fact ,  Zygobothria  is  twice  apt  to  be  the  victim  of  Meteorus,  which 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS.  267 


goes  through  two  generations  before  the  tachinid  has  entered  its 
second  stage. 

Table  XI  lias  been  prepared  for  the  purpose  of  showing  these  inter- 
relations graphically.  It  is  to  be  understood,  of  course,  that  not 
in  every  instance  have  the  exact  relations  thus  set  forth  been  actually 
observed;  but  it  is  perfectly  safe  to  say  that  they  are  not  only  within 
the  bounds  of  probability,  but  that  they  actually  occur  in  nature. 
The  only  point  concerning  which  doubt  is  felt  is  in  the  hyperparasit - 
ism  of  Kntedon  upon  Pteromalus, wheD  Pteromalus  itself  is  hyperpara- 
sitic  upon  Apanteles  or  Meteoms. 

Tabi.k  XI. — Poetibh  interrelation*  between  parasite*  hibernating  in  brown-tail  eater- 
pi  liars. 


Primary  parasites. 


Pteromalus  egragha 
A  panicles  1  ae  te  i- 


Meteoius  vcrsirolor 


Zygobothria  nldj 

iul.1. 


Secondary  super-  or 
hyj>er-para*;ites. 


Monodontome  r  u  s 

;ir»'l|s. 


Kntedon  alhit  arsis.1 
Ttero  rn  aim  egre- 

gmaJ  - 
Mesoehorus  pallipes. 

Moiiodonto  in  ••  r  u  s 

a*reus.» 
\  | >a ii  t  e  1 1>  s  la<  •»•!- 

eolor.1 


Pte  ro  mains  egre- 

gius.'  * 
A  pan  teles  laetei- 
color.2 


\t. •Tunis  v.TM.  uldr  -'. 

Monodont  o  nie  r  n  s 

tereus.1 
Pteromalus  egre- 

pius.2 


Ted  iary  super-  or 
h\|>er-parasites. 


Kntedon  alliit  arsis. 


Pterom  a  1  u  s  egre- 


Pterom  al  u  s  egre- 

Kius.i 
Mcstx  horus  pallipes. 

Monodonto  merus 

Tint.1 
Kntedon  alhitarsis.' 

Pterom  a  1  us  egre- 

gtOS.1  - 
.Mesoehorus  pallipes.1 

Mono<lonto  in erus 

aureus.1 
Pt  ero  in  a  1  u  s  egre- 

gius.i  2 


Kntedon  alhitarsis. 


(Quaternary  super- 
or  hyper-parasites. 


Kntedon  all »it ar- 
sis.1 


Kntedon    all  »it  ar- 
sis.* 

Pteromalus  e^r«>- 
gius.2 


Bntedon   alhit  ar- 
sis.' 

Pteromalus  f^re- 
gius.2 


Kntedon   alhit  ar- 
sis.1 


Qntnqotnary  super- 
or  hypea  paraeiiofl. 


Bntedon  alhitar- 
sis.' 


Do.' 


Ilyperparasitic  relations.  -  Suj>e.-parasit  ie  relat  ions. 

PEDK  I  l.OIDKS   VKNTHICOSUS  NEWP. 


During  the  winter  of  190.8-9  trouble  was  experienced  in  the  work 
of  breeding  Pteromalus,  the  exact  nature  of  which  was  not  imme- 
diately apparent.  There  were  numbers  of  the  reproduction  experi- 
ments in  which  the  proportionate  number  of  progeny  to  parents  used 
was  much  below  that  which  had  hitherto  been  secured  as  the  result 
of  similar  work  in  the  previous  spring.  An  examination  of  the  nests 
of  the  brown-tail  moth  which  had  been  used  in  these  experiments 
disclosed  the  presence  of  vast  numbers  of  the  adults  and  young  of  a 
mite,  determined  by  Mr.  Nathan  Banks  as  Pediculoides  ventricosus 
Newp.    The  gravid  female-  were  attached  to  the  caterpillars  of  the 


268  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

brown-tail  moth,  or  to  the  larvse  or  pupae  of  the  parasite,  indiscrimi- 
nately, and  in  some  of  the  reproduction  cages  practically  every  host 
and  parasite  had  been  attacked. 

It  was  not  known  where  these  mites  came  from,  but  it  was  pre- 
sumed that  they  were  brought  in  from  the  field  upon  nests  of  the 
brown-tail  moth.  By  the  time  that  they  had  been  discovered  they 
were  in  practically  everything  in  the  laboratory.  Even  tachinid 
puparia  were  not  immune  to  attack,  and  there  were  numerous 
instances  in  which  the  wandering  young  had  forced  their  way  through 
tight  cotton  plugs,  which  would  ordinarily  have  prevented  the  pas- 
sage of  bacteria. 

Much  time  and  trouble  was  necessary  before  the  laboratory  was 
finally  cleared  of  the  pest;  but  it  was  finally  accomplished  by  the 
rigid  separation  of  every  rearing  cage  containing  life  which  had 
been  present  before  the  invasion  became  apparent  from  those  which 
were  begun  afterwards.  The  general  cleaning  up  and  policy  of  seg- 
regation proved  effective,  and  by  spring  the  last  of  the  mites  appeared 
to  have  died;  nor  has  a  single  specimen  been  observed  since. 

As  parasites  of  the  brown-tail  moth  the  mites  were  singularly  effec- 
tive. If  it  were  possible  to  bring  about  a  general  infestation  of  the 
nests  in  the  early  fall,  it  would  doubtless  result  in  the  destruction  of 
a  very  large  proportion  of  the  hibernating  caterpillars;  but  unfortu- 
nately this  seems  to  be  not  at  all  practicable.  It  is  not  even  certain 
that  the  parasite  was  actually  brought  into  the  laboratory  in  nests 
of  the  brown-tail  moth,  though  this  would  seem  to  be  the  most  likely 
explanation  of  its  presence. 

The  fact  that  its  presence  has  never  once  been  detected  in  any  of 
the  many  thousands  of  similar  nests  which  have  been  brought  in  at 
other  times  indicates  rather  conclusively  that  it  is  not  actually  an 
enemy  of  any  consequence  in  the  field. 

PTEROMALUS  EGREGIUS  FORST. 

It  was  quite  late  in  the  spring  of  1905  before  the  senior  author  was 
able  to  organize  a  corps  of  European  collectors,  and  as  a  consequence 
only  a  very  small  quantity  of  parasite  material  was  imported  during 
t\w  summer  of  that  year;  but  during  the  fall  and  winter  following, 
well  within  a  year  after  the  work  was  first  authorized  by  the  Massa- 
chusetts  Legislature,  importation  was  begun  in  earnest.  More  than 
100,000  hibernating  nests  of  the  brown-tail  moth  were  received  from 
abroad  that  winter,  and  since  scarcely  anything  was  surely  known 
of  the  parasites  which  were  likely  to  be  reared  from  them,  the  early 
discovery  of  the  hibernating  brood  of  Pteromalus  egregius  (fig.  60, 
p.  263)  was  hailed  with  satisfaction.  The  circumstance  has  already 
been  the  subject  of  comment  in  an  earlier  section. 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS. 


269 


Tn  the  spring  of  1906  some  40  large  tube  cages  (PL  X,  fig.  1),  each 
capable  of  accommodating  several  thousand  nests,  were  constructed 
after  the  model  of  a  cage  which  had  been  successfully  used  for  a  some- 
what similar  purpose  in  California.  Hardly  had  the  nests  been  placed 
in  these  newly  constructed  cages  before  the  caterpillars  began  issuing 
in  extraordinary  numbers,  and  with  them  many  thousands  of  adult 
parasites,  representing  a  great  variety  of  species.  Monodontoim  / US 
&reus  was  about  the  first  to  issue,  and  with  it  was  a  quantity  of 
Habrobracon  brevicomis.  A. little  later  Pteromalus  egregius  (fig.  05) 
appeared  in  an  abundance  which  exceeded  that  of  all  the  other  para- 
sites taken  together,  and  it  WSS  followed  shortly  afterwards  by 
swarms  of  it>  own  little  parasite,  determined  by  Dr.  Ashmead  as 
Entedon  albitarsis. 


Yiga^.— Pteromalus  egregius:  Adult  female.  Greatly  enlarged.   (Original. ) 


Mr.  Titus  at  once  recognized  Entedon  as  hyperparasit ic  and  pro- 
ceeded as  assiduously  to  destroy  it  as  he  was  assiduous  in  saving  the 
Pteromalus.  Of  the  myriad  of  other  parasites  issuing,  the  vast 
majority  were  represented  by  so  lew  individuals  as  to  render  it  verv 
improbable  that  any  among  them  were  eneni'vs  of  the  caterpillars  of 
the  brown-tail  moth.  Nearly  all  of  the  more  common  species,  aside 
from  Pteromalus  and  Entedon.  were  representative  of  genera  or 
groups  of  genera  well  known  to  be  parasitic  upon  Cynipidae,  of  which 
large  numbers  issued  from  the  galls  on  oak  leaves  that  had  been  used 
by  the  caterpillars  in  the  construction  of  their  nests.  There  remained 
as  possible  parasites  of  the  caterpillars  of  the  brown-tail  moth  only 
Habrobracon  brevicomis,  Pteromalus  egregius,  and  Monodontojnerus 
sereus. 

It  looked  for  a  time  as  though  the  Habrobracon  might  be  para- 
sitic upon  the  hibernating  caterpillars,  and  quite  a  large  number  of 


270 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


them  was  liberated  in  the  spring  of  1906,  but  it  was  later  discovered 
that,  like  Monodontomerus,  they  merely  sought  the  hibernating  nests 
for  the  protection  which  was  thus  afforded  during  the  winter.  One 
colony  of  Monodontomerus  was  also  established  early  in  the  spring 
of  1906,  but  almost  immediately  thereafter  the  action  was  regretted 
on  account  of  the  doubts  which  Dr.  Ashmead  expressed  concerning 
the  host  relations  of  this  species.  He  was  certain  that  it  was  a  para- 
site of  Diptera,  and  that  it  could  not  be  a  primary  parasite  of  the  gipsy 
moth  or  of  the  brown-tail  moth.  As  events  have  since  abundantly 
proved,  he  w^as  right  and  wrong  at  one  and  the  same  time. 

The  separation  of  the  parasites  from  the  exceedingly  large  number 
of  caterpillars  which  issued  coincidently,  and  the  subsequent  sepa- 
ration of  Pteromalus  from  the  remaining  species,  was  a  task  of  huge 
proportions,  but  eventually  it  was  accomplished,  and  some  40,000 
Pteromalus  were  liberated  in  several  localities,  as  indicated  on  the 
accompanying  map.  At  the  same  time  an  attempt  was  made  to  deter- 
mine the  habits  of  the  species,  and  reproduction  experiments  were 
conducted,  using  the  active  caterpillars  of  the  brown-tail  moth  as 
hosts. 

The  females  were  frequently  observed  to  take  pecidiar  interest  in 
these  active  caterpillars  of  the  brown-tail  moth.  They  would  fre- 
quently alight  upon  their  backs  and  appear  to  oviposit,  and  since 
nothing  was  then  known  or  suspected  of  the  well-nigh  total  depravity 
of  this  species  in  so  far  as  its  habits  of  oviposition  are  concerned,  it  was 
only  natural  to  suppose  that  it  was  really  possible  for  successful  ovi- 
position to  take  place  under  these  circumstances.  Nothing  less  was 
expected  than  that  there  would  prove  to  be  a  second  generation  of 
the  parasite,  developing  within  the  active  caterpillars,  or  perhaps  in 
the  pupse. 

Attempts  to  discover  some  trace  of  this  generation  were  futile,  but 
failure  could  not  altogether  be  attributed  to  the  fact  that  such  a 
generation  did  not  exist.  As  it  happened,  every  one  of  the  several 
colonies  of  the  parasite  was  situated  within  a  territory  to  the  north- 
ward of  Boston  over  which  the  brown-tail  moth  was  exceedingly 
abundant.  Late  in  the  spring  the  host  of  caterpillars  was  suddenly 
destroyed  by  an  epidemic  of  a  fungous  disease  which  was  so  complete 
and  overwhelming  as  to  leave  very  few  survivors.  Even  now,  four 
years  later,  the  brown-tail  moth  has  not  reached  its  former  abundance 
over  a  considerable  portion  of  the  territory  affected,  notwithstanding 
that  there  has  been  steady  and  fairly  rapid  annual  increase  through- 
out tli  is  period.  It  looked,  in  fact,  as  though  the  parasites  had  suffered 
to  an  even  greater  extent  than  their  hosts  (since  they  were  not  so 
thoroughly  well  established),  and  failure  to  recover  Pteromalus  from 
the  field  during  the  summer,  or  even  during  the  winter  following,  was 
thought  to  be  the  result  of  the  epidemic  of  disease. 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS. 


271 


Another  importation  of  the  hibernating  nests  consisting,  like  the 
first,  of  about  100,000  from  various  localities  in  Europe,  was  received 
the  next  winter  and  handled  in  the  same  manner  as  was  the  other,  but 
a  flairs  at  the  laboratory  did  not  run  as  smoothly  as  they  might  in  the 
spring  of  1907  at  about  the  time  when  the  Pteromalus  were  issuing. 
Mr.  Titus  was  absent  on  account  of  sickness  which  eventually  forced 
him  to  resign  from  his  position  at  the  laboratory,  and  neither  Mr. 
('raw  ford,  who  first  took  his  place,  nor  the  present  incumbent,  who 
finally  assumed  charge  the  latter  part  of  May.  was  sufficiently  familiar 
with  the  work  to  carry  it  on  to  as  good  advantage  as  Mr.  Titus  would 
have  done  had  he  retained  his  health.  Partly  on  this  account  and 
partly  on  account  of  weather  conditions  which  were  very  unfavorable 
to  the  issuance  of  the  parasites,  only  about  40, 000  of  the  Pteromalus 
were  reared  and  liberated.  As  before,  they  were  colonized  in  various 
local  it  ics  within  the  infested  area  as  soon  after  their  emergence  as  was 
pract  icable,  and  as  before  attempts  to  secure  laboratory  reproduction 
WOTS  made. 

All  of  these  attempts  to  scenic  the  reproduction  of  the  parasite 

in  1906  or  in  1  (.M)7  failed,  since  only  active  caterpillars  of  the  brown- 
tail  moth  or  gipsy  moth  were  used.  All  soils  of  theories  to  explain 
this  were  formulated,  but  that  which  seemed  the  most  reasonable  at 
the  time,  namely,  that  the  parasite  did  n<»t  actually  reproduce  upon 
active  caterpillars  or  pupn,  but  only  upon  inactive  caterpillars  after 
the  const  met  ion  of  their  nest  s  in  1  he  fall,  conk  I  not  be  given  an  actual 
test,  since  inactive  caterpillars  were  not  available.  An  attempt  to 
cany  the  living  Pteromalus  adults  through  the  summer  did  not  suc- 
ceed, and  with  the  death  of  the  individuals  in  confinement,  and  the 
almost  immediate  disappearance  of  those  which  were  liberated  in  the 
field,  the  investigations  were  necessarily  brought  to  a.  close. 

Meanwhile,  as  will  be  detailed  later  on.  a  Variety  of  other  parasites 
was  found  to  be  present  as  minute  lnrvse  which  hibernated  within  the 
still  living  caterpillars,  and  for  the  purpose  of  securing  these  as  well 
as  an  additional  supply  of  the  Pteromalus,  further  extensive  importa- 
tions of  the  nests  of  brown-tail  moths  were  made  dining  the  winter 
of  1007-8.  A  radical  modification  in  the  policy  of  the  Laboratory 
was  inaugurated  at  the  same  time,  and  instead  of  discontinuing  its 
activities  dining  the  winter  months,  the  experiment  was  made  of 
keeping  it  open  for  the  purpose  of  conducting  a  series  of  winter  inves- 
tigations, and  the  study  of  the  hibernating  caterpillars  of  the  brown- 
tail  moth  and  of  their  parasites  was  selected  as  the  subject  for  the  first 
winter's  work. 

The  first  lot  of  nests  arrived  from  abroad  in  December,  and  instead 
of  awaiting  the  coming  of  spring  they  w  ere  immediately  brought  into 
a  warmed  room  in  the  hope  that  the  parasites  might  thereby  be  forced 
into  activity.    The  experiment  was  successful.    The  first  of  the 


272 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Pteromalus  began  to  issue  coincidently  with  the  beginning  of  the  new 
year,  and  they  were  at  once  supplied  with  a  quantity  of  nests  of  the 
brown-tail  moth  collected  in  the  open  and  containing  living  cater- 
pillars. In  most  cases  the  females  almost  instantly  entered  these 
nests  and  oviposited  upon  the  still  dormant  caterpillars  (fig.  66)  with 
the  result  that  in  three  and  four  weeks  large  numbers  of  a  second 
generation  began  to  issue.  This  successful  outcome  to  what  was 
considered  to  be,  until  that  time,  an  experiment  of  rather  doubtful 
utility,  was  very  encouraging,  since  it  was  at  once  evident  that  any 
desired  number  of  Pteromalus  might  easily  be  reared  in  captivity. 
Accordingly  the  work  of  rearing  it  on  a  large  scale  was  begun,  with 
the  result  that  by  the  end  of  March  American  nests  which  contained 
the  progeny  of  some  100,000  individuals  were  available  for  coloni- 
zation. 

Meanwhile  large  numbers  of  nests  of  the  brown-tail  moth — several 
thousand,  in  fact — had  been  collected  in  the  neighborhood  of  the 
colonies  which  had  been  planted  in  1906  and  1907  and  no  Pteromalus 
issued  from  them.  It  was  evident  that  the  colonization  experiments 
of  the  spring  of  1907  were  no  more  successful  than  those  of  the  spring 
before,  and  it  was  no  longer  possible  to  consider  the  bad  results  as  due 
to  the  unusual  mortality  of  the  brown-tail  moth  in  the  vicinity  of  the 
colonies.  It  was  necessary  to  seek  some  other  explanation  for  this 
apparent  failure  to  establish  the  one  parasite  which  had  been  imported 
and  colonized  in  wholly  satisfactory  numbers,  and  it  was  thought  that 
this  might  be  found  in  the  circumstances  under  which  the  parasites 
were  reared  and  liberated. 

In  1906  and  1907  the  adults  had  been  liberated  in  the  field  some  two 
or  three  weeks  sooner  than  they  would  normally  have  issued  as  adults 
on  account  of  their  development  having  been  hastened  by  the  storing 
of  the  nests  of  the  brown-tail  moth  at  an  artificially  high  temperature 
during  the  time  that  they  were  in  transit  from  Europe.  This,  it  was 
believed,  might  be  responsible  for  the  fact  that  the  species  had  failed 
to  establish  itself  and  it  was  planned  to  do  things  very  differently  in 
the  spring  of  1908. 

In  accordance  with  these  plans  the  nests  containing  the  brood  (as 
well  as  quantities  of  healthy  caterpillars)  were  placed  in  large  tube 
cages,  which  were  fitted  with  a  "  tanglef ooted  "  shield  within,  intended 
to  prevent  the  emergence  of  the  caterpillars  without  hindering  the 
egress  of  the  winged  parasites,  and  four  colonies,  each  of  which  was 
estimated  to  consist  at  the  very  least  of  50,000  of  the  parasite  larvae, 
were  located  in  four  widely  separated  localities  in  eastern  Massachu- 
setts. The  cages  were  simply  taken  into  the  field  and  left,  so  that  the 
parasites  were  free  from  the  moment  of  their  emergence. 

Considerable  trouble  was  experienced  at  first  on  account  of  the 
"  tanglef  ooted"  shields  failing  to  do  all  that  was  expected  of  them 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS. 


273 


in  the  matter  of  preventing  the  escape  of  the  caterpillars,  but  aside 
from  that,  the  experiment  promised  to  be  highly  successful.  Instead 
of  losing  track  of  the  parasites  immediately  following  their  liberation, 
they  were  found  to  be  present  in  abundance  in  and  about  these  cages 
throughout  May  and  June,  and  even  in  July  Mr.  Mosher  (who  con- 
ducted this  work)  observed  a  few  alive  and  apparently  waiting  until 
the  next  generation  of  hibernating  caterpillars  woidd  be  open  to  their 
at  tack. 

Not  all  of  the  Pteromalus  brood  was  liberated  in  this  manner,  but 
a  part  of  the  artificially  infested  nests  was  placed  in  cold  storage4  at 
a  constant  temperature  of  approximately  30°  F.  and  kept  during  the 
summer  and  until  the  formation  of  the  brown-tail  moth  nests  in  the 
fall.  Then  a  part  of  them  was  removed  as  a  check  on  the  condition 
of  the  remainder,  and  when  it  was  certain  that  many,  if  not  most  of 
the  Pteromalus  had  survived,  a  considerable  number  of  them  was 
allowed  to  is>ne  in  the  open  in  a  locality  where  they  would  find  an 
abundance  of  fresh  nests  of  the  brown-tail  moth  ready  at  hand. 
Others  of  the  stored  Pteromalus  were  held  for  the  purposes  of  winter 
reproduction,  in  case  the  further  colonization  of  the  parasite  seemed 

worth  attempting. 

At  iiist  it  appeared  that  the  colonic-  of  I'.tOS,  both  spring  and  fall, 
were  successful.  In  the  vicinity  of  each  of  them  (but  particularly  of 
that  which  was  planted  in  the  fall)  the  larva1  of  the  parasite  were 
found  in  the  nests  of  the  brow  n-t ail  moth,  and  for  the  first  time  it 
waf  known  to  have  lived  over  summer  out  of  doors.  lv\  tensive  rearing 
work  was  organized  in  the  laboratory,  with  the  intention  of  securing 
at  least  1,000,000  for  coloni/at ion  in  1909,  and  certain  technical  inves- 
tigations into  the  life  of  the  parasite,  which  were  begun  in  the  spring 

of  190S,  were  continued. 

The  results  of  these  biological  investigations  soon  became  startling 
in  their  nature.  Gradually,  as  the)'  were  continued,  and  the  results 
of  one  experiment  after  another  became  apparent,  a  tale  of  insect 
duplicity  was  unfolded  the  like  of  which  has  never  been  quite  equaled 
in  any  similar  investigation.  It  is  not  possible  to  give  the  story  in 
anything  like  complete  detail,  but  a  brief  summary  ought  to  be  pre- 
sented, if  for  no  other  purpose  than  to  illustrate  the  degradation  to 
which  a  parasite  may  sink. 

It  was  found  that  the  instinct  of  the  female  Pteromalus  was  first 
to  seek  the  immediate  vicinity  of  the  feeding  caterpillars,  or  of  the 
nests  or  molting  webs  which  they  had  deserted,  and  second  to  ovi- 
posit upon  nearly  anything  which  she  encountered,  providing  it 
resembled  in  the  slightest  degree  a  dormant  caterpillar  of  the  brown- 
tail  moth  inclosed  in  its  hibernating  web  (fig.  66).  Attempted 
oviposition  upon  active  caterpillars  was  only  one  of  innumerable 
96677°— BalL  01—11  18 


274 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


illustrations  of  the  lengths  to  which  she  would  go  in  satisfying  her 
crude  and  unreasoning  instincts.  She  would  oviposit  with  as  much 
apparent  freedom  upon  a  dead  and  decomposing  caterpillar,  or  the 
fragment  of  skin  torn  from  such  a  one,  as  upon  a  living  caterpillar. 
Quite  an  extensive  series  of  experiments  was  to  have  been  made  to 
determine  the  lengths  to  which  she  would  go,  but  these  experiments 
were  discontinued  after  a  time  because  there  hardly  seemed  to  be 
any  limit  beyond  the  purely  physical.  .No  Pteromalus  was  ever 
induced  to  oviposit  in  any  tachinid  puparium,  nor  in  any  other 
insect  protected  by  a  hard  shell,  but  almost  any  small,  inactive,  and 
soft-bodied  insect,  especially  if  it  were  inclosed  in  a  thin  silken  web 
or  cocoon,  and  provided  it  was  in  the  near  vicinity  of  caterpillars  of 
the  brown-tail  moth  or  of  their  webs,  would  be  attacked  and  usually 


Fig.  66.— Pteromalus  egregius:  Female  in  the  act  of  oviposition  through  the  silken  envelope  containing 
hibernating  caterpillars  of  the  brown-tail  moth.    Greatly  enlarged.  (Original.) 

without  hesitation.  The  cocoons  of  small  Hymenoptera,  such  as 
Apanteles  and  Limnerium,  were  especially  attractive,  and  would  be 
attacked  whether  associated  with  the  brown-tail  moth  or  not. 

The  results  of  this  indiscriminate  oviposition  were  very  varied. 
Eggs  deposited  upon  dead  caterpillars  of  the  brown-tail  moth  inva- 
riably perished  except  in  one  instance,  in  which  the  caterpillars  were 
freshly  killed  and  "pasteurized."  Upon  this  occasion  a  small  pro- 
portion of  the  larvae  lived,  and  at  least  one  went  through  to  maturity. 
Upon  active  caterpillars  of  the  brown-tail  moth  and  even  upon  inactive 
caterpillars  removed  from  the  silken  envelopes  with  which  they 
surround  themselves  within  their  nests,  oviposition  was  never  suc- 
cessful if  the  caterpillar  moved  to  any  extent  afterwards.  Even  the 
hibernating  caterpillars,  removed  from  their  nests,  will  move  about 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS. 


275 


a  very  little  as  a  rule,  and  the  least  motion  was  sufficient  to  dislodge 
the  egg  or  young  larva  of  the  parasite. 

Oviposition  upon  any  other  host  was  equally  unsuccessful,  provided 
that  the  host  was  free  to  move  about  to  any  extent,  but  whenever 
it  was  confined  within  the  limits  of  a  cocoon,  and  was  not  too  large, 
it  usually  fell  a  victim  to  the  parasite.  Especially  was  this  true  of 
the  hibernating  larvae  of  hymenopterous  parasites  within  their 
cocoons,  and  from  these  the  largest  and  finest  Pteromalus  were 
reared. 

If  the  parasite  or  h\  nienopterous  larva  w  as  very  small,  as  in  the 
instance  of  the  larva  of  Apanteles.  it  was  very  likely  to  be  killed  bv 
the  Pteromalus  in  the  process  of  oviposition  and.  as  a  common  result, 
her  progeny  would  perish  also. 

Evidence  to  indicate  that  the  female  parasite  possesses  discrimi- 
native powers  which  enable  her  intelligently  to  select  suitable  hosts 
for  her  young  is  wholly  lacking,  and  in  consequence,  when  several 
individuals  are  given  access  to  a  single  nest  of  the  brown-tail  moth, 
the  chances  are  that  all  of  them  will  concentrate  their  at  lack  upon 
the  few  caterpillars  which  chance  to  be  most  readily  accessible,  to 
the  exclusion  of  all  others.  The  outcome  is  one  of  the  manifold 
phases  of  superparasitism.  The  larva*  hatching  from  the  superabun- 
dance of  eggs  are  unable  to  reach  their  full  development.  They  ma 
complete  their  transformations  but  the  adults  produced  are  small, 
weak,  and  in  extreme  instances  w  holly  unfit  for  further  reproduction. 

In  the  work  of  rearing  the  parasite  for  colonization  purposes,  no 
matter  how  many  parent  Pteromalus  were  used,  the  number  of  cater- 
pillars which  were  parasitized  by  them  would  be  a  small  percentage 
of  those  in  the  nests  exposed  to  their  attack,  and  invariably  when 
more  than  a  few  females  were  used  as  parents  the  nests  had  to  be 
torn  open,  so  as  to  expose  a  large  number  of  caterpillars  equally. 
Otherwise  the  progeny  would  be  so  small  as  to  be  practically  worth- 
less for  further  reproduction,  colonization,  or  anything  else.  This 
in  itself  was  sufficient  to  render  Pteromalus  of  very  much  less  value 
from  an  economic  standpoint,  and  the  extraordinary  avidity  with 
which  it  attacked  the  cocoons  of  other  hymenopterous  parasites  was 
anything  but  a  point  in  its  favor.  Most  especially  was  this  true 
when  the  life  and  habits  of  Apanteles  lacteicolor  Yier.  were  taken  into 
consideration.  It  soon  became  evident  that  Pteromalus  w  as  pecul- 
iarly fitted  to  act  as  its  most  dangerous  enemy,  and  since,  between 
the  two,  Apanteles  was  much  the  more  promising  parasite,  it  was 
decided  to  abandon  all  further  effort  toward  the  introduction  of 
Pteromalus,  and  the  work  of  rearing  was  discontinued. 

Some  250,000  larvae  and  pupae  were  on  hand  at  the  time  when  this 
decision  was  reached,  and  these  were  placed  in  cold  storage.  It  was 
considered  probable  that  the  species  was  already  introduced,  if  it 


276  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

were  possible  to  do  so,  as  the  result  of  the  elaborate  colonization 
work  already  described,  and  that  any  harm  which  might  result  was 
probably  already  done,  so  it  was  determined  to  use  these  larvse  and 
pupae  for  the  purpose  of  giving  the  parasite  one  more  opportunity  to 
retrieve  a  lost  reputation.  The  brood  lived  through  the  summer  in 
cold  storage  without  much  loss,  and  in  the  fall  one  tremendous  colony 
of  some  200,000  individuals  was  established  in  the  midst  of  a  tract 
of  small  oak,  well  infested  with  nests  of  the  brown-tail  moth.  The 
adults  issued  at  a  time  when  there  was  nothing  to  prevent  their 
entering  these  nests  and  ovipositing  immediately,  and  there  were 
enough  of  them  to  destroy  all  of  the  caterpillars  of  the  brown-tail 
moth  within  a  considerable  radius.  There  were  many  larvae  to  be 
found  in  the  nests  that  winter,  but,  as  was  the  case  in  the  laboratory, 
only  a  few  of  the  more  exposed  caterpillars  were  attacked. 

A  rather  elaborate  series  of  nest  collections  was  made  within  a 
radius  of  a  mile  of  the  center  of  the  colony,  but  the  data  obtained 
were  of  little  consequence.  From  only  a  part  of  the  many  lots  of 
nests  did  any  of  the  parasite  issue,  and  its  probable  rate  of  dispersion 
was  not  definitely  indicated.  One  lot  of  nests  collected  a  little  over 
a  mile  away  produced  a  few  individuals,  and  this  was  the  only 
instance  in  which  it  could  be  shown  to  have  traveled  so  far. 

At  the  same  time  large  collections  were  made  in  the  vicinity  of  the 
1908  colonies,  from  which,  it  will  be  remembered,  some  few  parasites 
had  been  recovered  the  winter  before.  In  no  instance  was  it  again 
recovered,  and  there  was  everything  to  indicate  that  it  had  failed 
to  establish  itself. 

No  attempt  whatever  was  made  to  rear  it  for  colonization  in  1910, 
and  until  the  beginning  of  the  winter  of  that  year  it  was  considered 
that  the  story  of  Pteromalus  in  America  was  complete.  It  is  the 
unexpected  which  usually  happens  in  the  gipsy-moth  parasite  labora- 
tory, however,  and  even  as  the  rough  manuscript  for  the  last  few 
pages  was  being  prepared,  Chapter  II  of  the  history  of  Pteromalus 
egregius  in  America  was  about  to  begin. 

Every  winter  since  that  of  1906-7,  to  and  including  the  present, 
an  increasingly  large  number  of  the  hibernating  nests  of  the  brown- 
tail  moth  have  been  collected  from  various  localities  throughout 
(  astern  Massachusetts  and  confined  in  tube  cages  in  the  laboratory. 
In  the  first  two  winters  this  was  done  for  the  express  purpose  of 
recovering  Pteromalus  and,  as  has  been  already  stated,  without 
result.  In  the  winter  of  1908-9,  it  was  found  that  Monodontomerus 
was  to  be  recovered  in  this  manner  over  a  considerable  territory  and 
under  conditions  which  were  both  interesting  and  instructive. 
Accordingly,  beginning  with  that  winter,  the  collections  have  been 
made  genera]  throughout  the  territory  in  which  it  was  thought  likely 
(lint  Monodontomerus  would  occur,  and  with  less  reference  to  the 


PARASITES  HIBERNATING  IX  BROWN-TAIL  WEBS. 


277 


localities  in  which  Pteromalus  had  been  colonized.  Several  thou- 
sands were  thus  collected  in  1909-10  (as  may  be  seen  by  reference  to 
Table  X)  and  a  much  larger  series  of  collections  was  planned  for  the 
winter  of  1910-11. 

On  the  face  of  the  results  of  this  work  during  the  two  previous 
winters,  nothing  was  much  less  likely  than  that  Pteromalus  should 
be  recovered  from  any  of  these  collections  of  nests.  When  a  few 
specimens  of  a  ptemmalid  which  looked  very  much  like  it  did  issue 
early  in  December,  they  were  accorded  a  rather  cool  reception,  and 
made  to  identify  themselves  b\-  reproducing  upon  hibernating  cater- 
pillars of  the  brown-tail  moth  in  confinement.  Before  such  identi- 
fication was  complete,  it  was  rendered  unnecessary  through  the  issuance 
of  considerable  numbers  of  what  could  no  longer  be  questioned  as  the 
true  Pteronxilus  ((jrajnis  from  no  less  than  10  lots  of  nests  collected 
in  different  towns  scattered  all  the  way  from  Milford.  Mass.,  down 
near  the  Rhode  Isiand  line,  to  Dover  and  Portsmouth,  X.  II.,  just 
across  the  Piscataqua  River  from  Maine.  At  the  time  of  writing 
they  are  still  emerging  from  the  collected  nests,  and  the  extent  of 
their  dispersion  is  not  yet  known,  but  Mr.  II.  K.  Smith,  who  is  attend- 
ing to  the  rearing  cages,  has  prepared  a  map  (Plate  XXVi  .showing 
lie  location  of  the  original  colonies  as  well  as  the  towns  from  which 
recovery  has  been  made  the  present  winter. 

Sufficient  data  have  already  been  accumulated  to  make  certain 
the  astounding  fact,  that  as  a  result  of  the  colonization  work  •  •<>n- 
ducted  between  19(H)  and  1(.M)S,  the  parasite,  is  now  thoroughly 
established  over  a  territory  which  undoubtedly  includes  portions  of 
four  States,  and  during  the  period  of  its  dispersion  it  spread  itself  out 
so  thin  as  to  make  its  recovery  impossible  except  in  the  immediate 
vicinity  of  the  colony  sites,  and  for  a  short  period  immediately  fol- 
lowing colonization.  Until  this  time  Monodontomerus  has  held  the 
record  for  rapid  dissemination,  but  this  record  is  now  eclipsed. 

It  is  impossible  to  determine  whether  the  first  of  the  colonies  were 
after  all  successful,  or  whether  they  actually  died,  as  was  supposed, 
and  success  finally  resulted  from  the  very  much  larger  colonies  in 
1908.  If  the  early  colonies  lived,  it  means  that  no  less  than  four 
years  elapsed  before  any  evidence  to  that  effect  was  forthcoming. 
This  fact,  in  its  relation  to  circumstances  attending  the  colonization 
of  another  parasite,  Apanteles  fulvipes,  which  seems  not  to  have 
succeeded  in  establishing  itself  any  more  than  Pteromalus  appeared 
to  have  established  itself  as  a  result  of  those  early  colonizations,  will 
sustain  some  hope  for  the  ultimate  recovery  of  this  parasite  until 
1912  or  1913. 

If,  on  the  other  hand,  the  establishment  of  Pteromalus  resulted 
from  the  very  much  larger  and  in  every  way  satisfactory  colonizations 
of  1908,  it  may  mean,  in  its  reference  to  Apanteles  fulvi pes,  that  very 


278 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


much  larger  colonies  will  be  necessary  before  we  can  hope  to  see  that 
species  established  in  America.  To  colonize  it  under  more  satisfac- 
tory conditions  than  those  which  prevailed  in  1909  would  be  well- 
nigh  impossible  except  at  a  very  heavy  expenditure,  because  the 
favorable  conditions  in  1909  were  primarily  due  to  the  unusual  coinci- 
dental circumstance  of  an  early  season  in  Japan,  and  a  late  season 
in  Massachusetts.  Such  coincidences  can  not  be  depended  upon, 
and  without  them,  a  tenfold  expenditure  over  that  of  1909  would  be 
insufficient  to  secure  equally  favorable  conditions  for  the  establish- 
ment of  the  species,  and  a  proportionately  larger  expenditure  to 
better  them. 

The  story  of  Pteromalus  has  been  given  at  length  because  of  the 
bearing  which  it  has  upon  the  question  of  what  constitutes  a  satis- 
factory colony  of  any  species  of  parasite.  Except  in  a  few  instances, 
of  which  Calosoma  and  Anastatus  are  conspicuous,  we  frankly  do 
not  know  the  answer,  and  it  is  only  through  the  study  of  such  phe- 
nomena as  those  which  have  accompanied  the  recovery  of  Pteromalus 
that  we  are  able  to  judge  the  probable  character  of  the  answer  in  the 
instance  of  those  parasites  which  for  some  obscure  reason  or  another 
have  failed  to  make  good  their  establishment  in  America. 

APANTELES  LACTEICOLOR  VIER. 

The  story  has  already  been  told  of  how,  during  the  winter  of  1905-6, 
some  100,000  hibernating  nests  of  the  brown-tail  moth  were  imported, 
placed  in  large  tube  cages  in  the  laboratory  at  North  Saugus,  and 
how  some  60,000  Pteromalus  and  countless  thousands  of  cater- 
pillars of  the  brown-tail  moth  issued  into  the  attached  tubes,  and 
were  sorted  with  difficulty.  There  is  not  a  single  published  record 
outside  of  those  emanating  from  the  laboratory,  so  far  as  was  then 
known,  or  is  known  now,  which  suggested  the  possibility  of  this 
particular  sort  of  caterpillar  harboring  other  parasites  than  those 
which  issued  as  adults  from  its  nests.  Mr.  Titus  recognized  that 
this  might  well  be  possible,  however,  and  rather  with  the  purpose 
of  determining  the  fact  than  with  the  expectation  of  securing  such 
parasites  in  any  quantity  for  liberation,  he  caused  some  of  the  cater- 
pillars to  be  fed  in  confinement  and  under  observation.  His  fore- 
sight was  well  rewarded  when,  in  the  course  of  time,  a  number  of 
cocoons  of  an  Apanteles  (fig.  67)  was  found  in  these  cages,  and  the 
fact  that  at  least  one  parasite  hibernates  within  the  living  caterpillars 
was  demonstrated. 

The  following  spring  he  laid  his  plans  for  the  wholesale  rearing  of 
t  his  parasite  and  whatever  other  parasites  might  chance  to  be  present. 
A  considerable  aumberof  wood  mid  wire-screen  cages  (PI.  XXVI,  fig.  1 ), 
modifications  of  the  familiar  Riley  type,  was  procured,  and  as  the 
caterpillars  issued  from  the  cages  containing  the  second  large  importa- 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS. 


279 


tion  of  hibernating  nests  in  the  spring  of  1907  they  were  placed  in 
these  cages  and  fed.  As  a  result  of  his  enforced  absence  from  the 
laboratory  at  a  critical  period  these  cages  lacked  the  proper  atten- 
tion, and  things  went  wrong  with  many  of  them.  A  few,  however, 
were  measurably  successful,  and  eventually  about  1,000  of  the 
Apanteles  were  reared  and  colonized.  Met  corns  was  discovered  to 
have  similar  hibernating  habits,  and  Zygobothria  was  also  reared 
under  circumstances  which  were  sufficient  to  indicate  its  hibernating 
habits  to  the  satisfaction  of  the  junior  author  of  this  bulletin,  but 
not  to  that  of  the  senior.  The  Apanteles,  in  accordance  with  what 
was  then  the  policy  of  the  laboratory  with  regard  to  parasite  coloniza- 
tion, were  liberated  in  no  less  than  three  widely  separated  localities. 
None  of  the  colonies,  so  far  as  known,  was  successful. 

As  anyone  who  was  unfortu- 
nate enough  to  be  associated 
with  the  laboratory  during  the 
spring  and  summer  of  1907  will 
undoubtedly  be  willing  to 
testify,  the  discomfort  caused  by 
handling  quantities  of  caterpil- 
lars and  cocoons  of  the  brown- 
tail  moth  was  literally  dread- 
ful. The  poisonous  spines  upon 
the  young  caterpill  a  rs  are 
neither  so  abundant  nor  BO  viru- 
lent as  those  upon  the  older 
caterpillars,  but  they  are  bad 
enough,  and  the  task  of  feeding 
the  inmates  of  the  numerous 
cajres   which    contained  some 


Fig.  f.7. — Aj>anta 


It  female  and  co- 


coon.  Much  enlarged.  (Original.) 
thousands  was  a  t  ask  of  no  lit  t  le 

magnitude  and  one  involving  much  physical  discomfort.  The  instant 
the  door  of  one  of  these  cages  was  opened,  if  the  day  was  warm  and  its 
occupants  active,  a  variable,  but  usually  a  large  number  would  crawl 
outside,  and  to  attempt  to  brush  them  back  was  but  to  aiTord  op- 
portunity for  more  to  escape.  Consequently  thousands  did  escape 
and  had  to  be  brushed  up  and  destroyed  after  each  day's  feeding. 
To  keep  the  cages  clear  of  debris  was  well-nigh  out  of  the  question, 
and  every  time  that  some  attempt  was  made  to  clean  them  out  more 
thousands  of  caterpillars  escaped  and  had  to  be  destroyed. 

When  the  Apanteles  and  the  Meteorus  cocoons  were  discovered  to 
be  present  in  variable  abundance  in  several  of  the  cages  trouble  began 
in  earnest,  because  they  were  for  the  most  part  firmly  attached  to 
the  sides,  or  cunningly  concealed  in  the  midst  of  an  accumulation  of 
unconsumed  food,  so  that  much  time  was  required  to  find  and  remove 


280  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

them.  During  this  operation  the  caterpillars,  stirred  into  unusual 
activity,  were  crawling  over  everything  in  the  immediate  vicinity,  but 
more  particularly  over  the  outside  of  the  cage  and  the  person  of  the 
operator. 

If  a  sufficient  number  of  these  caterpillar  parasites  were  to  be  reared 
to  make  possible  satisfactory  colonies  another  year,  it  was  obviously 
exceedingly  desirable  to  devise  some  other  means  of  feeding  the 
caterpillars  than  that  afforded  by  the  closed  cage,  and  accordingly, 
in  the  winter  of  1907-8,  when  the  first  active  caterpillars  began  to 
emerge  from  the  nests  which  had  been  kept  in  the  warmed  part  of 
the  laboratory  for  the  purpose  of  securing  Pteromalus,  all  sorts  of 
experiments  were  made  in  the  hope  of  discovering  some  method 
whereby  the  disadvantages  above  recounted  might,  at  least  in  part, 
be  obviated.  The  feeding  tray  illustrated  herewith,  was  the  result  of 
these  experiments,  and  as  soon  as  it  was  found  to  be  practicable, 
enough  to  accommodate  several  thousand  caterpillars  were  con- 
structed, and  one  wing  of  the  laboratory  11  annex/'  illustrated  in 
Plate  XXVI,  figure  2,  and  Plate  XXVII,  was  fitted  for  their  accom- 
modation. 

In  all  respects  these  trays  were  a  success.  There  was  occasionally 
some  trouble  caused  by  the  caterpillars  finding  or  constructing  a 
"bridge,"  by  which  they  passed  from  the  interior  of  the  tray  directly 
to  the  frame  above  the  concealed  band  of  "tanglefoot,"  but  when 
sufficient  care  was  used  in  feeding  and  in  searching  for  bridges  before 
they  were  completed  this  was  almost  completely  done  away  with. 

It  was  manifestly  impossible  to  feed  more  than  a  very  small  part 
of  the  caterpillars  from  the  many  thousands  of  nests  which  had  been 
imported  during  this  winter,  and  accordingly  the  caterpillars  from  a 
few  nests  in  each  lot  were  fed  in  small  trays  in  the  laboratory  during 
the  late  winter  and  early  spring,  and  the  extent  to  which  they  were 
parasitized  by  Apanteles  was  thus  determined.  The  most  highly 
parasitized  nests  were  saved,  and  the  larger  part  of  those  less  highly 
parasitized  were  destroyed  forthwith,  since  it  was  no  longer  desired 
to  save  the  Pteromalus  which  might  be  reared  from  them. 

A  good  many  Apanteles  were  reared  in  the  course  of  this  work,  and 
since  they  issued  long  before  the  resumption  of  insect  activities  out 
of  doors  they  were  used  in  a  series  of  reproduction  experiments  upon 
active  caterpillars  of  the  brown-tail  moth  feeding  upon  lettuce  indoors. 
It  was  found  to  be  easy  to  secure  reproduction  when  caterpillars 
which  had  not  molted  since  leaving  the  nest  were  used  as  hosts,  but 
if  they  had  molted  once  successful  reproduction  was  secured  with 
great  difficulty  or  not  at  all.  The  adult  Apanteles  were  very  far  from 
being  as  strong  and  hardy  as  the  adult  Pteromalus  and  could  not  be 
kept  alive  to  deposit  more  than  a  small  part  of  their  eggs.  There 
were,  other  reasons,  too,  why  reproduction  upon  caterpillars  in  confine- 


Bui.  91,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agriculture 


Plate  XXVI. 


Fig.  2.— Interior  of  One  of  the  Laboratory  Structures,  Showing  Trays  Used  in 
Rearing  Apanteles  lacteicolor  in  the  Spring  of  1909.  (Original.) 


View  of  the  Laboratory  Interior,  Showing  Cages  in  Use  for  Rearing  Parasites 
from  Hibernating  Webs  of  the  Brown-Tail  Moth  in  the  Spring  of  1908. 
(Original.) 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS. 


281 


ment  could  not  be  looked  upon  as  a  feasible  method  for  obtaining  the 
parasites  for  liberation,  and  all  ideas  of  laboratory  reproduction  work 
on  a  large  scale  were  regretfully  abandoned  before  the  spring  was  far 
advanced. 

A  program  for  the  colonization  of  Apanteles  during  the  year  1908 
was  definitely  formulated  as  the  direct  result  of  this  experimentation, 
by  which  it  was  hoped  to  afford  the  parasite  the  best  possible  oppor- 
tunity for  speedy  establishment.  In  accordance  with  this  plan  the 
nests  which  had  been  found  to  contain  the  more  highly  parasitized 
caterpillars  were  divided  into  three  lots.  The  larger  of  these  was 
placed  in  the  same  form  of  tube  cage  which  was  used  for  the 
Pteromal us-rearing  work  in  1906  and  1907:  the  next  larger  was 
placed  in  cold  Btorage,  and  the  nests  remaining  were  brought  into  the 
laboratory  toward  the  end. of  March  and  the  caterpillars  forced  into 
premature  activity.  There  was  not  very  much  room  available  for 
this  indoors,  so  that  the  number  of  nests  thus  treated  was  decidedly 
limited,  but  from  the  caterpillars  issuing  from  them  no  less  than 
2.000  Apanteles  cocoons  were  secured  during  the  latter  part  of  April, 
and  the  adult  Apanteles,  to  the  number  of  about  1,300,  which  issued 
from  them  were  liberated  in  the  one  colony  in  the  field  just  as  the 
caterpillars  of  the  brown-tail  moth  were  issuing  from  their  nests  and 
beginning  to  feed  out  of  doors. 

It  was  known  that  under  natural  conditions  the  parasite  never 
issued  as  an  adult  at  this  season  of  the  year,  but  it  was  reasonably  cer- 
tain that  it  would  immediately  reproduce  upon  the  small  caterpillars 
which  in  a  week  or  two  more  would  be  so  large  as  to  make  reproduc- 
tion impossible.  It  was  hoped  in  this  manner  to  give  the  individuals 
liberated  in  this  colony  a  certain  advantage  over  those  liberated  later 
by  allowing  them  superior  opportunities  for  immediate  reproduction 
and  incident  ally  an  opportunity  for  one  more  generation  during  the 
year  than  would  be  possible  in  colonies  established  at  a  later  date. 

To  a  certain  extent  these  expectations  were  realized.  It  was  posi- 
tively ascertained  that  the  parasite  did  take  advantage  of  the  oppor- 
tunity offered  and  that  it  did  actually  pass  one  generation  upon  the 
newly  active  caterpillars  of  its  chosen  host.  The  experiment  is  not 
known  to  be  a  practical  success,  however,  because  all  subsequent 
attempts  to  recover  Apanteles  from  nests  of  the  brown-tail  moth 
collected  in  the  vicinity  of  this  colony  have  failed. 

As  soon  as  the  caterpillars  in  the  nests  which  had  been  placed  in 
the  large  cages  became  active  they  were  transferred  to' the  larger 
i  rays  which  had  been  provided  especially  for  them  (PL  XXVI,  fig.  2), 
and  fed  first  with  lettuce  and  later  with  fresh  foliage  collected  in  the 
field.  They  did  remarkably  well  at  first,  and  about  May  20  the 
cocoons  of  Apanteles  began  to  appear  in  the  trays  in  large  numbers. 
The  collection  of  these  cocoons  and  their  removal  to  small  cages  for 


282  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

the  rearing  of  the  Apanteles  was  simplicity  itself,  compared  with  the 
similar  process  the  year  before.  A  large  sheet  of  paper,  thickly  per- 
forated with  small  holes,1  or  what  was  equally  suitable,  a  strip  of 
ordinary  mosquito  netting,  would  be  spread  over  the  pile  of  debris 
in  each  tray  and  fresh  food  placed  on  it.  In  the  course  of  24  hours 
the  great  majority  of  the  caterpillars  would  have  crawled  upon  this 
paper  or  netting,  and  could  be  removed  instantly,  and  with  scarcely 
any  disturbance,  to  a  fresh  tray.  The  sorting  over  of  the  contents 
of  the  tray  in  which  they  had  been  feeding,  for  the  cocoons  of  their 
parasites,  could  then  be  conducted  without  the  annoyance  of  their 
presence,  and  with  a  minimum  of  discomfort.  This  is,  of  course,  the 
same  method  used  in  feeding  the  silkworm  of  commerce. 

In  all  some  15,000  cocoons  were  secured  in  this  manner,  but  only 
about  10,000  of  the  adults  were  reared  and  liberated.  Some  100  of 
the  cocoons  produced  the  secondary  parasite  MesocJiorus  pallipes, 
and  a  considerably  larger  number  a  small  pteromalid,  which  was 
vaguely  familiar  in  appearance,  but  which  was  not  at  that  time  recog- 
nized as  identical  with  Pteromalus  egregius,  concerning  which  so  much 
has  already  been  written. 

The  Apanteles  were  carefully  separated  from  their  enemies  and 
three  colonies  were  established  in  the  field.  Two  of  these  were 
rather  small,  but  one  of  them  was  made  very  large,  and  to  comprise 
more  than  two- thirds  of  the  total  number  reared.  It  was  no  longer 
a  question  that  the  small  colony  was  sometimes  a  mistake,  and  that 
it  was  invariably  safer  to  liberate  large  colonies  and  to  establish  the 
species  first  of  all,  and  to  bring  about  dispersion  later,  if  artificial 
dispersion  should  appear  to  be  necessary. 

It  is  interesting  to  note,  in  this  connection,  that  neither  in  1909 
nor  1910  was  it  possible  to  find  any  trace  of  the  Apanteles  in  the 
neighborhood  of  either  of  the  two  smaller  colonies  mentioned  above, 
while  from  the  larger  it  was  recovered  in  1909,  and  by  1910  had  spread 
to  a  distance  of  several  miles  at  least. 

The  third  lot  of  nests,  which  was  placed  in  cold  storage  before  the 
caterpillars  became  active  in  the  spring,  was  left  there  until  early  in 
July,  when  it  was  removed.  A  part  of  the  caterpillars  immediately 
became  active,  but  it  was  at  once  evident  that  many  of  them  had 
died  as  a  result  of  the  unnatural  conditions.  The  weather  was 
exceedingly  hot  immediately  following  and  suitable  food  for  the  young 
caterpillars  could  not  be  obtained.  In  consequence,  a  great  many  of 
them  died  from  one  cause  or  another,  or  from  a  combination  of  sev- 
eral ;  the  larger  part  of  the  caterpillars  died  soon  after  having  become 
active,  and  it  seemed  as  though  those  containing  the  Apanteles 
suffered  much  greater  proportionate  mortality  than  the  others;  in 
any  even),  only  about  250  of  the  cocoons  were  secured,  when  it  was 

1  This  paper  was  Originally  imported  from  France  for  use  in  a  similar  manner  in  roaring  silkworms. 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS. 


283 


hoped  to  secure  10  times  that  number  at  the  very  least.  The  few 
thai  were  reared  were  placed  in  the  Held  in  accordance  with  the  pro- 
gram mapped  out  the  winter  before,  just  about  the  time  when  the 
new  generation  of  brown-tail  caterpillars  was  beginning  to  construct 
winter  nests,  and  when  there  was  no  possible  excuse  for  failure  on  the 
part  of  the  Apanteles  to  reproduce  to  the  full  extent  of  its  powers. 
In  so  far  as  the  puny  colony  thus  planted  could  possibly  be  expected 
to  succeed,  this  one  was  a  success.  Quite  a  number  of  cocoons  was 
found  the  next  spring  in  tin4  molting  webs  of  the  caterpillars  from 
the  near-by  nests  and  it  was  evident  that  if  the  Apanteles  had  been 
reared  as  successfully  at  this  season  of  the  year  as  it  had  been  hoped 
would  be  the  case,  no  betier  plan  for  the  rearing  and  colonization  of 
the  species  could  be  devised. 

There  was  no  possibility  of  judging  the  success  or  failure  of  the 
Apanteles  colonies  of  1908  until  the  following  Bpring  at  the  earliest, 
and  whether  they  succeeded  or  failed  it  was  obviously  desirable  to 
continue  the  work  at  Leasl  one  year  more.  Accordingly,  more  nests 
were  imported  in  the  winter  of  1908  9,  and  from  among  them  those 
which  were  the  most  highly  parasitized  were  selected  for  rearing 
the  Apanteles.  No  attempts  to  establish  colonies  out  of  season  were 
made  t  his  t  ime. 

Partly  as  a  result  of  experience  gained  the  year  before,  partly 
because  more  caterpillars  were  fed,  and  partly  because  several  among 
the  lots  of  Dests  received  this  year  were  very  heavily  parasitized,  the 
number  of  Apanteles  reared  and  colonized  was  about  23,000,  or  twice 
the  number  of  the  year  before.  They  were  distributed  in  three  colo- 
nies, one  of  which  was  near  the  site  of  the  only  successful  late  spring 

planting  of  L908.  There  was  do  apparent  necessity  for  this,  but  the 
accuracy  of  the  theory  of  the  large  colony  and  establishment  at  any 
cost  was  becoming  more  and  more  evident,  and  it  was  resolved  to  leb 
no  opportunity  slip  by  which  a  possible  advantage  might  be  lost. 
The  two  remaining  outlying  colonies  were  each  as  large  as  the  suc- 
cessful colony  of  1908,  and  Apanteles  was  recovered  in  the  spring  of 
1910  in  the  vicinity  of  both. 

[Jy  the  spring  of  1909  the  pteromalid,  which  had  commonly  been 
reared  from  the  Apanteles  cocoons,  was  identified  beyond  question  as 
Pteromalus  egregius.  It  was  found  that  the  females  persistently 
haunted  the  trays  in  which  the  caterpillars  were  feeding,  and  that 
they  were  very  free  in  ovipositing  in  the  cocoons  of  Apanteles  when- 
ever they  encountered  them.  It  was  discovered,  furthermore,  that 
if  tin1  weather  w  as  hot  and  humidity  low,  the  Apanteles  larva  or  pupa 
in  the  cocoon  attacked  would  die  and  dry  up  before  the  Pteromalus 
was  full-fed,  so  that  nothing  would  emerge.  A  few  of  the  unhatched 
cocoons,  of  which  there  were  more  than  25  per  cent  in  the  summer  of 
190S,  were  saved  and  examined  after  these  facts  were  known,  and  in 


284  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

several  of  them  what  were  almost  certainly  the  eggs  and  very  young 
larva?  of  Pteromalus  were  found.  It  thus  became  evident  that  at 
least  a  portion  of  this  unfortunate  mortality  was  due  to  hyper- 
parasitism  by  Pteromalus,  a  considerable  number  of  which  had  been 
free  in  the  compartment  where  the  caterpillars  of  the  brown-tail  moth 
had  been  feeding.  In  1909  pains  were  taken  to  prevent  a  recurrence 
of  these  circumstances,  and  as  a  result  only  a  very  few  of  the  cocoons 
were  lost  through  attack  by  Pteromalus.  That  Pteromalus  was  to  be 
considered  as  an  aggressive  enemy  of  Apanteles  could  no  longer  be 
doubted,  and  when  it  was  remembered  that  the  adults  naturally 
emerged  from  the  nests  of  the  brown-tail  moth  in  the  open  at  almost 
the  precise  time  (PL  XXVIII,  fig.  1)  when  the  Apanteles  larvae  were 
emerging  and  spinning  their  cocoons,  more  often  than  otherwise  in 
the  outer  interstices  of  these  same  nests,  and  that,  furthermore,  the 
Pteromalus  was  prone  to  linger  in  the  vicinity  of  these  nests  in  prefer- 
ence to  any  other  place,  its  true  duplicity  was  at  last  realized. 

A  much  smaller  number  of  over-wintering  nests  of  the  brown-tail 
moth  was  imported  during  the  winter  of  1909-10  than  during  any 
other  since  the  beginning  of  the  work,  more  for  the  purpose  of  securing 
Zygobothria,  if  possible,  than  for  the  rearing  of  additional  Apanteles. 
The  large  trays  were  used  as  before  (PL  XXVI,  fig.  2)  for  the  rearing 
of  a  number  of  the  caterpillars  in  the  spring,  and  10,000  or  more 
Apanteles  were  reared  and  liberated  in  one  colony  at  some  distance 
from  any  of  the  others. 

Until  late  in  the  summer  of  1910  considerable  doubt  was  felt  as 
to  the  ability  of  this  Apanteles  to  pass  through  the  summer  months 
successfully  in  large  numbers.  That  it  was  able  to  live  from  June  to 
August  or  September  at  all  was  rather  more  than  was  expected  when 
it  was  first  liberated.  When,  in  1908  and  1909,  it  proved  its  ability 
to  do  that  much  it  remained  to  be  determined  whether  it  was  going  to 
be  dependent  upon  an  alternate  host  during  that  period  or  not,  and 
if  dependent  whether  a  sufficient  abundance  of  such  hosts  would  be 
found  in  America  to  support  as  many  of  the  parasites  as  would  needs 
be  carried  through  the  summer,  if  it  were  to  become  an  aggressive 
enemy  of  the  brown-tail  moth  when  this  insect  is  in  abundance. 

It  was  with  much  satisfaction,  therefore,  that  Apanteles  lacteicolor 
Vier.  was  recovered  as  a  parasite  of  Datana  and  Hyphantria  late  in  the 
summer  of  1910.  Both  hosts  are  common  at  that  season  of  the  year 
in  Massachusetts,  and  both  are  parasitized  to  a  considerable  extent 
by  tachinids.  It  is  certain  that  the  Apanteles  will  develop  at  the 
expense  of  1  hese  parasites  as  well  as  that  of  their  hosts,  and  the  chances 
are  good  t  hat  it  will  replace  them  to  a  certain  extent,  without  bringing 
about  a  serious  reduction  in  the  prevailing  abundance  of  these  hosts; 
in  short,  that  it  will  find  a  permanent  place  for  itself  in  the  American 
fauna. 


Bui.  91,  Bureau  o'  Entomology,  U.  S.  Dept.  of  Agriculture 


Plate  XXVIII. 


Fig.  2.— View  of  Laboratory  Yard,  Showing  Various  Temporary  Structures, 
Rearing  Cages,  etc.  A,  A,  Out-of-Door  Insectary  Used  for  Rearing 
Predaceous  Beetles.  (Original.) 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS. 


285 


The  diversity  in  the  host  relations  of  the  parasite  thus  indicated  is 
also  encouraging.  If  it  is  capable  of  attacking  arctiid  as  well  as 
notodontid  caterpillars  with  as  much  apparent  freedom  as  it  does 
liparids,  there  ought  always  to  be  plenty  of  available  hosts  to  cany 
the  species  over  the  two  or  three  months  which  must  elapse  after  its 
emergence  from  the  hibernating  brown-tail  moth  before  it  can  attack 
the  young  caterpillars  of  the  same  species  for  a  second  generation. 
1 1  was  hoped  for  a  time  that  it  would  succeed  in  passing  one  generation 
upon  the  gipsy  moth,  but  although  it  has  been  forced  to  oviposit  in 
gipsy-moth  caterpillars,  and  its  larva*  have  upon  a  single  occasion 
attained  their  full  development  upon  this  host,  there  is  no  indication 
that  it  evei-  attacks  it  voluntarily  in  the  field. 

It  is  interesting  and  perhaps  significant  that  in  it>  relations  with 
Datana  it  affects  the  host  caterpillars  exactly  as  in  its  relations  with 
the  brown-tail  moth.  The  caterpillars  died  before  the  emergence  of 
the  parasite  larva?,  and  were  left  as  nothing  more  than  mere  skins  con- 
taining a  small  quantity  of  a  clear  liquid.  In  this  respect,  Apanteles 
lm  t<  [color  Vier.  differs  materially  from  .1.  solitari us,  or  from  many 
other  among  its  congener^,  which  leave  the  host  in  a  living  condition 
but  so  seriously  affected  as  to  be  unable  to  feed  again. 

Just  as  the  proof  of  this  bulletin  is  being  read  (June  12,  1911)  word 
is  received  from  the  laboratory  at  Melrose  Highlands  that  4,000 
cocoons  of  this  parasite  have  been  secured  from  brown-tail  moth  webs 
taken  in  the  field  in  Maiden  and  other  towns. 

APANTELES  0ON8PERSJS  FISKE. 

In  the  summer  of  1910  several  boxes  of  the  cocoons  of  an  Apanteles 
parasitic  upon  the  Japanese  brown-tail  moth,  Fji])r<>v1is  conspersx 
Butl.,  were  received  at  the  laboratory  through  the  kindness  of  Prof. 
S.  I.  Kuwana.  All  of  them  had  hatched  at  the  time  of  receipt,  and 
the  circumstance  would  hardly  be  worthy  of  mention  were  it  not  for 
the  fact  that  the  adults  which  were  dead  in  the  boxes  proved  upon 
examination  by  Mr.  Viereck  to  be  identical  in  all  structural  character- 
istics with  Apanteles  lacteicolorYier.  It  would  appear  that  here  was 
still  another  example  of  that  phenomenon  which  has  several  times 
been  mentioned  without  having  been  particularly  designated,  but 
which  is,  in  effect,  the  existence  of  what  has  been  termed  "physio- 
logical" or  "biological"  species. 

It  is  not  so  difficult  to  conceive  as  to  find  proof  of  the  existence  of 
two  species  which  are  so  nearly  alike  structurally  as  to  be  indistin- 
guishable by  any  taxonomic  characters  commonly  recognized,  but 
which  are,  at  the  same  time,  different.  This  difference  may  be 
exemplified  by  the  sex  of  the  parthenogenetically  produced  offspring, 
as  in  the  instance  of  the  European  and  American  races  of  Tricho- 
gramma  pretiosa.    It  may  lie  in  the  instincts  of  the  female,  which  lead 


286 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


her  to  select  certain  hosts  in  preference  to  certain  others,  as  in  the 
-instance  of  the  American  and  European  races  of  Parexorista  chelonise. 
Again,  it  may  be  in  the  ability  of  the  young  larvae  to  complete  their 
development  upon  a  certain  host,  as  in  the  case  of  Tachina  mella  and 
TacMna  larvarum.  Or  again,  it  may  be  that  the  difference  lies  as  be- 
tween Apanteles  lacteicolor  Vier.  and  A.  conspersse  Fiske  in  the  methods 
of  attacking  the  host. 

As  has  already  been  recounted,  no  less  than  45,000  adults  of 
Apanteles  lacteicolor  Vier.  have  been  reared  at  the  laboratory  and  lib- 
erated in  the  field.  In  addition  a  very  large  number  has  been  reared 
under  close  observation  during  the  winter  or  spring,  and  there  has 
been  a  large  number  of  more  or  less  successful  reproduction  experi- 
ments conducted,  in  most  instances  with  great  care.  In  all  this  time 
there  has  not  been  a  single  exception  to  the  rule,  that  the  larva  of 
Apanteles  lacteicolor  Vier.  is  solitary,  and  kills  its  host  before  issuing 
from  its  body.  Nothing  whatever,  either  in  the  field,  or  in  the  many 
experiments  in  reproduction,  or  in  the  occurrence  of  the  parasite  in 
shipments  of  larger  caterpillars  from  Europe,  has  indicated  in  any 
way  that  it  may  ever  attack  the  large  caterpillars  successfully,  or 
that  it  is  ever  anything  else  than  solitary. 

Had  Apanteles  conspersse  Fiske  been  received  as  a  parasite  of  the 
Japanese  brown-tail  moth  without  other  data  than  the  mere  rearing 
record  it  would  undoubtedly  have  been  considered  as  identical  with 
Apanteles  lacteicolor  Vier.,  but  it  is  impossible  so  to  consider  it  in  view 
of  the  fact  that  it  is  not  solitary  but  gregarious;  that  it  attacks,  not 
the  small  but  the  large  caterpillars,  and,  if  appearances  of  the  material 
from  Mr.  Kuwana  were  not  deceiving,  that  the  host  is  left  alive  instead 
of  being  killed  before  the  emergence  of  the  parasite  larva.  These 
differences  are,  or  ought  to  be,  sufficient  to  make  of  it  another  species. 

It  is  not  at  all  improbable  that  if  it  were  given  the  opportunity  it 
would  attack  the  caterpillars  of  the  European  brown-tail  moth,  and  it  is 
hoped  that  enough  can  be  collected  in  Japan  and  forwarded  to  Amer- 
ica to  make  the  experiment  possible. 

METEORUS  VERSICOLOR  WESM. 

A  very  few  specimens  of  this  parasite  were  imported  in  1906  with 
caterpillars  of  the  brown-tail  moth  and  the  gipsy  moth  from  several 
European  localities.  In  1907,  as  already  stated  in  the  account  of 
Apanteles  lacteicolor  Vier.,  a  few  specimens  of  Meteorus  (fig.  68)  were 
reared  from  caterpillars  imported  in  hibernating  nests  the  winter  be- 
fore;. There  were  very  few,  less  than  100  all  told,  and  not  enough  to 
colonize  with  any  likelihood  of  success.  It  was  therefore  decided  to 
use  them  in  a  series  of  reproduction  experiments,  on  the  chance  that 
a  much  Larger  number  might  be  reared  for  colonization. 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS. 


287 


There  were  plenty  of  caterpillars  of  the  brown-tail  moth  available 
and  the  smallest  that  could  be  found  were  confined  in  a  cage  with  the 
first  of  the  parasites  that  were  reared.  Oviposition  was  not  observed, 
and  the  parent  adults  did  not  live  very  long,  but  the  caterpillars  did 
very  well  for  about  10  days,  after  which  the  cocoons  of  Meteorus 
began  to  be  found  in  the  cages  in  most  gratifying  numbers.  It 
seemed  as  though  success  was  assured,  and  other  similar  experiments 
were  immediately  begun  in  the  hope  that  some  method  would  be 
found  for  prolonging  the  life  of  the  adult  parasites  in  confinement 
and  securing  more  abundant  reproduction. 

'\  he  days  of  rejoicing  over  tliis,  the  first  successful  reproduction 
experiment  with  any  of  the  parasites  imported  in  1 1)07,  were  very  few. 
In  about  a  week  the  adults  began  to  issue  from  the  cocoons,  and 
all  proved  to  be  males.  It 
Looked  like  a  curious  coinci- 
dence at  first,  but  when  one 
after  another  of  the  various  lots 
of  cocoons  hatched  and  out  of 
the  total  of  every  single 

individual  was  of  the  one  sex, 
it  was  evident  that  something 
serious  was  the  matter.  Where 
the  trouble  lay  was  not  ascer- 
tained at  that  time,  nor  has  it 
been  determined  as  the  result 
of  Other  experiments  similarly 
conducted  in  later  years.  In 
all,  24  1    adult    Meteorus  have 

been  reared  in  confinement ,  and 
among  them  there  have  been 
just  5  females,  not  one  of  which 
was  secured  until  the  late  sum- 
mer of  L908.  Breeding  Meteorus  on  a  Large  scale  for  colonization 
purposes  under  circumstances  like  these  can  not  be  considered  as  an 
economically  profitable  venture. 

The  numbers  of  Meteorus  reared  from  the  caterpillars  imported  in 
the  hibernating  nests  were  increased  by  the  addition  of  some  few  more 
secured  from  importations  of  full-fed  and  pupating  caterpillars  later 
in  the  season,  and  a  small  colony  was  planted  in  1907,  but  it  was  so 
small  as  to  make  its  success  more  than  doubtful,  and  it  was  deter- 
mined to  rear  enough  for  at  least  one  good  colony  in  the  spring  of 
1<)08. 

A  description  has  already  been  given  of  the  methods  winch  were 
perfected  during  the  winter  of  1907-8  for  the  rearing  of  Apanteles 
lacteicolor  Vier.  in  large  numbers  from  the  caterpillars  of  the  brown- 


Fig.  lis.—  Mc!(orus  versicolor:  Adult  female  and  co- 
coons.   Much  enlarged.  (Original.) 


288  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

tail  moth  imported  in  hibernating  nests,  and  these  methods  applied 
equally  well  to  Meteorus.  It  was  not  nearly  so  common  as  the  Apan- 
teles,  and  only  about  1,000  adults  were  secured  for  colonization. 
These  were  all  liberated  in  one  colony  at  a  convenient  place  from 
the  laboratory,  and  in  order  that  they  might  have  an  opportunity 
for  immediate  reproduction  a  very  large  number  of  retarded  cater- 
pillars of  the  brown-tail  moth  from  nests  which  had  been  placed  in 
cold  storage  during  the  winter  were  liberated  upon  trees  in  the 
immediate  vicinity. 

These  caterpillars  seemed  to  be  not  at  all  injured  as  a  result  of  their 
abnormal  experience,  but  immediately  began  to  feed  voraciously  and 
to  grow  apace.  That  they  were  injured  soon  became  evident,  but  it 
could  not  be  determined  whether  such  injury  was  due  to  the  enforced 
lengthening  of  their  period  of  hibernation,  to  the  hot  weather  which 
then  prevailed,  or,  possibly,  to  the  fact  that  the  foliage  was  much 
more  advanced  than  that  upon  which  caterpillars  newly  emerged  from 
hibernation  usually  fed.  They  began  to  die  at  an  alarming  rate 
inside  of  two  weeks,  and  when  it  was  time  to  make  a  collection  for  the 
purpose  of  determining  whether  the  Meteorus  had  found  them  or  not 
hardly  more  than  300  could  be  found  out  of  the  thousands  which  had 
been  liberated.  These  were  removed  to  a  tray  in  the  laboratory,  and 
from  June  23  to  July  15  no  less  than  76  Meteorus  cocoons  were 
removed.  From  these  43  adults,  of  which  16  were  females,  were 
reared. 

These  were  the  first  females  of  the  second  generation  which  had 
been  secured  at  the  laboratory,  and  a  part  of  them  was  used  in  a 
reproduction  experiment  similar  to  those  which  had  resulted  in  the 
production  of  males  the  previous  year.  Curiously  enough,  the  adults 
of  the  third  generation  reared  from  these  parents,  under  circumstances 
identical  with  those  which  had  been  used  in  earlier  reproduction 
experiments,  consisted  of  both  sexes,  there  being  5  females  out  of  a 
total  of  40.  These  were  the  first  females  of  the  species  ever  reared 
from  adults  in  confinement. 

In  the  spring  of  1909  the  caterpillars  from  a  few  nests  which  had 
been  collected  the  winter  before  in  the  vicinity  of  this  first  satisfactory 
field  colony  were  fed  in  the  laboratory,  and  from  them  a  few  cocoons 
of  Meteorus  were  secured.  It  was  certain  that  the  species  had  com- 
pleted the  cycle  of  the  seasons  in  the  open,  but  it  was  also  rather 
evident  that  it  was  not  very  common.  If  this  were  due  to  widespread 
dispersion,  as  might  easily  be  the  case,  it  might  possibly  result  in  the 
species  spreading  out  so  thin  as  to  be  lost,  and  it  was  resolved  to  place 
the  Meteorus  reared  in  1 909  in  the  same  general  vicinity,  on  the  theory 
thai  by  spreading  over  the  same  territory  the  colony  might  be  mate- 
rially strengthened  throughout.  This  was  done,  and  about  2,000 
individuals  were  liberated  during  that  spring  and  summer,  the  most 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS. 


289 


of  which  came  from  hibernating  caterpillars,  but  a  part  of  which  was 
imported  as  parasites  of  the  full-fed  and  pupating  caterpillars.  The 
experiment  of  colonizing  large  numbers  of  retarded  caterpillars  in  the 
vicinity  was  repeated,  and  with  similar  results  to  those  secured  in  the 
previous  season. 

In  1910  a  larger  number  of  the  cocoons  was  found,  but  at  the 
same  time  a  very  few  were  secured  from  the  caterpillars  which  had 
been  collected  in  the  vicinity  of  the  colony.  It  did  not  look  as  though 
much  was  to  be  expected  from  the  parasite  at  first,  but  when,  toward 
the  end  of  June,  collections  of  full-fed  caterpillars  were  made  from 
various  localities  for  the  purpose  of  determining  the  status  of  the 
tachinid  parasites,  the  results  were  much  more  encouraging.  Cocoons 
of  the  second  generation  of  Meteorns  were  soon  found  in  some  num- 
bers and  to  a  distance  of  a  mile  or  more  from  the  original  colony 
center.  Within  a  rather  limited  area  near  the  colony  center  they 
could  almost  he  said  to  he  abundant,  so  abundant  that  .">()  were  col- 
lected in  the  course  of  about  two  hours'  work.  They  are  far  from 
being  conspicuous  objects,  being  wholly  disassociated  from  the  cater- 
pillar which  served  as  host,  and  on  this  account  the  number  collected 
was  considered  to  indicate  a  very  satisfactory  abundance. 

Its  rate  of  dispersion,  so  far  as  indicated  by  the  results  of  the 
summer  work  upon  the  caterpillars  of  the  brown-tail  moth,  was  too 
slow  to  he  satisfactory,  but  in  the  early  fall  a  single  specimen,  defi- 
nitely determined  by  Mr.  Yiereck  as  of  this  species,  was  secured  from 
a  lot  of  caterpillars  of  the  white-marked  tussock  moth  collected  in 
the  city  of  Lynn,  some  7  miles  from  the  colony  site.  This  would 
indicate  a  rapidity  of  dispersion  in  excess  of  that  of  ( 'ompsilura, 
and  one  which  is  distinctly  satisfactory. 

Another  specimen  was  reared  in  the  fall  of  1910  from  a  caterpillar 
of  the  fall  webworm  collected  in  the  open,  and  this  was  also  con- 
sidered as  satisfactory  evidence  of  its  ability  to  exist  here.  At  the 
present  time  there  seems  to  be  every  reason  to  expect  that  it  will  be 
found  In  1911  over  a  more  considerable  territory  and  in  a  much 
greater  abundance  than  in  1910. 

ZYGO  BOTH  R I A  NIDICOLA  TOWNS. 

The  few  caterpillars  which  Mr.  Titus  saved  from  among  those 
emerging  from  the  hibernating  nests  in  the  spring  of  1906  all  died 
before  pupation,  and  no  other  parasite  than  Apanteles  and  a  single 
specimen  of  the  Apanteles  parasite,  Mesochorus  pallipes,  was  reared 
from  them.  In  1907  trouble  was  again  experienced  in  carrying  the 
caterpillars  from  imported  nests  through  to  maturity,  but  among  the 
t  housands  which  were  fed  in  the  cages  at  the  North  Saugus  laboratory, 
as  described  in  the  account  of  the  introduction  of  Apanteles,  a  few  did 

95677°— Bull.  91—11  19 


290 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


reach  the  point  of  pupation,  and  from  them  a  very  few  Zygobothria 
adults  (fig.  69)  were  reared.  There  was  no  ground  for  doubting  that  the 
tachinids  actually  issued  from  the  imported  caterpillars  of  the  brown- 
tail  moth  and  that  they  had  actually  been  present  as  hibernating 
larvae  within  the  caterpillars  when  they  were  received  from  Europe, 
but  at  the  same  time  the  circumstance  seemed  so  improbable  as  to  be 
refused  immediate  credence.  Confirmation  of  the  records  was  accord- 
ingly sought  in  1908,  and  preparations  were  made  to  carry  large 
numbers  of  the  caterpillars  from  imported  nests  through  to  maturity 
in  the  large  trays,  already  mentioned  in  the  discussion  of  Apanteles. 

For  a  time  everything  went  well,  and  the  caterpillars  passed  through 
three  of  the  spring  stages  and  assumed  the  colors  characteristic  of  the 

last  with  scarcely  any  mortality. 
Then,  for  some  reason,  they  ceased 
to  feed  freely,  and  began  to  die, 
and  even  those  which  did  feed 
ceased  to  grow.  Eventually  prac- 
tically all  of  them  died,  but  of  the 
few  which  survived  to  pupate,  a 
very  few  contained  the  parasite, 
and  although  only  about  half  a 
dozen  of  the  adult  Zygobothria 
were  reared,  they  were  sufficient 
to  prove  beyond  question  the  va- 
lidity of  the  earlier  conclusions. 
The  death  of  the  caterpillars  from 
imported  nests  in  1906  was  sup- 
posed to  be  due  to  the  epidemic 
of  fungous  disease  which  affected 
those  in  confinement  quite  as  gen- 
erally as  those  in  the  open,  and  in 
1907  death  was  presumed  to  be 
the  result  of  the  unsanitary  con- 
ditions which  resulted  from  the  use  of  the  closed  cages.  In  casting 
about  for  a  cause  in  1908,  the  drying  of  the  food  in  the  open  trays 
before  the  caterpillars  fed  upon  it  was  deemed  to  be  sufficient,  and 
consequently,  in  1909,  it  was  determined  to  use  extraordinary  precau- 
( ions  and  to  rear  a  large  number  of  the  tachinids  if  it  were  possible. 

In  the  early  spring  of  1909  a  considerable  number  of  the  imported 
caterpillars  was  dissected  before  they  began  to  feed,  and  in  some  lots 
a  high  percentage  was  found  to  contain  the  hibernating  larvse  of  the 
Zygobothria  (fig.  63,  p.  264).  These  lots  were  to  be  given  especial 
care,  and  little  doubt  w  as  felt  as  to  the  success  of  the  outcome, because 


Fig.  6X — Zygobothria  nidicola:  Adult  female,  with 
front  view  of  head  above  and  side  view  below. 
Much  enlarged.  (Original.) 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS.  291 


do  particular  difficulty  had  been  experienced  in  feeding  small  numbers 
of  the  caterpillars  from  native  nests  through  all  of  their  spring  stages. 

As  was  the  case  in  1907,  the  caterpillars  passed  through  the  first 
three  spring  stages  with  scarcely  any  mortality,  and,  as  before,  trouble 
was  finally  encountered.  In  the  first  place  a  considerable  propor- 
tion of  the  trays  was  infected  with  the  fungous  disease,  which  had 
been  accidentally  brought  in  from  the  field,  and  these  had  to  be 
destroyed  summarily.  There  were  still  a  number  of  the  trays  unaf- 
fected, however,  and  these  were  given  the  very  best  care  which  pre- 
vious success  with  native  caterpillars  and  failure  with  imported  cater- 
pillars suggested.  In  spite  of  all  the  results  were  exactly  as  before, 
and,  as  before,  only  an  insignificant  number  of  the  Zygobothria  com- 
pleted their  transformations.  It  was  all  the  more  surprising  because 
there  were  several  of  the  smaller  and  choicer  lots  which  were  kept  in 
a  cool,  airy  place,  side  by  side  with  trays  of  native  caterpillars,  fed 
upon  the  same  food  and  given  identically  the  same  attention,  and 
yet  every  single  individual  of  the  one  lot  died,  while  nearly  every 
individual  of  the  others  went  through  to  maturity. 

It  began  to  look  as  though  there  wa>  something  wrong  which  was 
outside  of  the  power  of  anyone  at  the  laboratory  l«>  remedy,  and  it 
was  resolved  to  test  the  matter  thoroughly  in  1910. 

The  caterpillar-dissection  work  which  was  begun  in  the  spring  of 
190!)  was  carried  <»n  quite  extensively  in  the  winter  of  1909-10,  and 
among  the  several  lots  of  hibernal  ing  Qfists  imported  that  winter  those 
which  came  from  Italy  and  France  were  found  to  contain  a  very  large 
percentage  of  caterpillars  hearing  the  larva1  of  Zygobothria  (fig.  63, 
p.  204).  These  caterpillars,  as  soon  as  they  emerged  from  these  nests 
in  the  spring,  were  separated  into  two  lots.  A  part  of  them  was  fed 
in  trays,  as  before,  and  another  part  was  immediately  placed  in  the 
open,  upon  small  oak  t  rees  w  hich  had  previously  been  cleared  of  native 
nests  of  the  brown-tail  moth  with  this  cud  in  view. 

The  caterpillars,  as  usual,  did  remarkably  well  in  both  cases,  and 
as  usual  the  three  spring  stages  wore  passed  in  the  normal  manner. 
At  the  end  of  that  time  those  which  had  been  fed  in  trays  began  to 
die,  and  those  in  the  open  to  disappear.  Mr.  Timberlake,  who  was 
assiduously  trying  to  follow  the  development  of  the  Zygobothria  mag- 
got-, throughout  their  later  stages,  found  it  increasingly  difficult  to 
find  the  caterpillars  in  very  large  numbers  in  the  field  where  they  had 
been  colonized,  and  finally  of  the  thousands  originally  present  only 
about  150  could  be  found.  These  had  reached  their  last  stage  by  this 
time,  and  they  were  collected  and  brought  into  the  laboratory. 
AY  it  bin  a  few  days  all  but  a  very  small  number  had  died,  and  as  there 
was  a  good  chance  that  a  few  native  caterpillars  were  present,  there 
was  nothing  to  indicate  that  all  of  the  survivors  were  not  native 
instead  of  imported. 


292 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


At  the  same  time  that  the  imported  caterpillars  were  liberated,  as 
above  described,  a  number  of  experiments  in  the  similar  colonization 
of  native  caterpillars  was  begun,  and  in  every  instance  in  which  they 
were  not  overtaken  with  some  well-defined  calamity — fire  in  one 
instance,  starvation  in  others — they  went  through  to  maturity  in 
large  numbers  and  in  a  perfectly  normal  manner. 

It  is  no  longer  to  be  doubted  that  in  the  case  of  tne  imported  cater- 
pillars some  element  other  than  any  which  is  operative  during  the 
feeding  period  of  the  caterpillars  in  the  spring  is  to  be  held  responsible 
for  their  wholesale  demise.  The  uniform  ill  success  which  has  invari- 
bly  attended  the  attempts  to  feed  the  brown-tail  caterpillars  from 
imported  nests  through  to  maturity  can  no  longer  be  considered  as 
either  coincidental  or  the  result  of  inexperience  in  this  sort  of  work. 
Something  else  is  responsible,  and  in  looking  about  for  parallel 
instances  the  results  which  have  attended  all  attempts  to  feed  cater- 
pillars of  the  brown-tail  moth,  no  matter  from  what  source,  out  of 
season,  are  possibly  to  be  considered  as  comparable. 

Hundreds  of  experiments  involving  the  feeding  of  native  and 
imported  caterpillars  upon  lettuce  during  the  late  winter  and  early 
spring  have  invariably  resulted  in  carrying  the  caterpillars  through 
their  first  three  spring  stages  and  in  their  death  before  pupation. 
This  may  be  due  to  the  character  of  the  food. 

A  smaller  number  of  experiments  in  feeding  caterpillars  of  the 
brown-tail  moth,  which  had  been  retarded  in  their  emergence  from 
the  winter  nests,  have  always  resulted  in  a  manner  not  altogether 
incomparable.  Many  thousands  of  these  caterpillars  have  been  kept 
in  cold  storage  for  about  one  month  after  they  would  normally  have 
issued  and  then  placed  upon  their  favored  food  plants  in  the  open. 
Upon  several  occasions  when  this  has  been  done  the  caterpillars  have 
fed  very  freely  at  first,  grown  rapidly,  and  appeared  to  be  perfectly 
healthy.  Then  they  would  begin  to  die,  almost  exactly  as  the 
imported  caterpillars  would  begin  to  die  in  the  fourth  spring  stage, 
and  it  does  not  appear  that  any  of  them  have  ever  completed  their 
transformations.  This  may  be  due  to  the  weather  conditions  and 
unsuitable  food.  It  is  believed  that  it  is  indirectly  due  in  this 
instance,  and  in  the  instances  of  the  caterpillars  from  imported  nests, 
to  the  fact  that  both  the  one  and  the  other  have  been  subjected  to 
abnormal  conditions  during  hibernation.  The  imported  nests  are 
always  exposed  for  a  considerable  period  during  the  winter  to  an 
unduly  high  temperature.  The  caterpillars  are  almost  upon  the 
point  of  becoming  active — sometimes  they  are  beginning  to  become 
active — when  the  nests  are  received  at  the  laboratory.  As  soon  as 
possible  after  their  receipt  they  are  placed  under  out-of-door  tem- 
perature  again,  with  t lie  result  that  the  caterpillars  become  inactive 
and  remain  so  until  the  time  when  they  would  normally  have  issued 


PARASITES  HIBERNATING  IN  BROWN-TAIL  WEBS. 


293 


from  the  nests  had  they  not  been  exposed  to  undue  warmth  during 
the  winter. 

It  makes  little  difference  whether  the  nests  are  exposed  to  one 
temperature  or  another  during  the  winter  so  long  as  the  caterpillars 
are  not  actually  stirred  into  activity;  the  date  of  final  emergence  in 
the  spring  remains  practically  unchanged.  Roughly  speaking,  if 
brown-tail  nests  are  exposed  to  a  constant  high  temperature  begin- 
ning at  any  time  during  October  the  caterpillars  will  die  without 
becoming  active;  during  November  they  will  die  if  kept  too  warm, 
but  become  active  in  a  little  over  a  month  if  kept  warm  and  humid; 
in  December  they  will  sometimes  become  active  by  the  l>t  of  January 
if  they  are  kept  fairly  humid,  and  during  January  they  will  nearly 
always  become  active  in  a  little  less  than  a  month,  no  matter  what 
the  conditions  of  humidity;  after  the  1st  of  February  activity  is 
resumed  in  something  like  two  week-:  after  the  Lsl  of  March  in  about 
one  week,  and  later  iu  a  few  day-.  If  kept  at  a  high  temperature 
for  three  weeks  in  December  or  two  weeks  iu  January  and  then  placed 
under  Datura]  conditions  for  the  resl  of  the  winter,  their  emergence 
will  not  be  appreciably  hastened  in  the  spring,  bill  if  the  attempts  to 
rear  Zygobot aria  from  imported  caterpillars  which  have  been  handled 
in  much  this  manner  arc  to  be  properly  interpreted,  subjection  to 
such  abnormal  conditions  results  in  m  subtle  disarrangement  of  the 
vital  processes,  and  the  insect  is  metaholisticallj  unbalanced. 

It  is  hardly  necessary  (to  return  to  the  story  of  Zygobothria)  to 

state  that  these  successions  of  almost  total  failures  were  not  only 
puzzling,  hut  decidedly  exasperating.  In  1910,  for  example,  we 
estimated  the  number  of  apparently  healthy  Zygobothria  larva*  on 
hand  in  apparently  equally  healthy  caterpillars  to  be  something  like 
40,000.  of  which  something  like  10.000  or  15,000  were  in  the  cater- 
pillars which  were  feeding  and  growing  in  a  perfectly  natural  manner 
in  the  open.  Long  before  it  was  time  for  these  caterpillars  to  pupate 
we  had  given  up  all  hope  of  more  than  an  insignificant  number  of 
these  parasites  going  through  to  maturity,  and,  as  a  matter  of  fact, 
there* is  no  record  of  a  single  one  among  them  going  through.  Every 
resource  had  been  exhausted  the  winter  before  in  attempting  to 
secure  a  shipment  of  uests  of  the  brown-tail  moth  in  good  condition 
from  some  locality  where  there  was  a  likelihood  of  Zygobothria 
occurring  in  abundance  as  a  parasite,  and  the  failure  was  even  more 
complete  than  usual.  There  remained  only  the  alternative  of  import- 
ing large  numbers  of  full-fed  and  pupating  caterpillars  of  the  brown- 
tail  moth,  collected  in  the  same  localities,  and  the  prospect  that  this 
would  be  successfully  accomplished  was  far  from  brilliant.  The 
senior  author  was  in  Europe  at  the  time  when  these  conclusions  were 
formed  and  was  putting  forth  his  utmost  endeavors  to  bring  about 
this  very  thing,  but  June  passed,  and  with  the  advent  of  July  it 


294 


PAEASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


became  certain  that  no  shipments  of  any  consequence  would  be 
received. 

It  was  known  that  the  parasite  could  be  secured  in  this  manner 
because  small  numbers  had  been  reared  from  the  imported  quantities 
of  full-fed  and  pupating  caterpillars  which  were  received  at  the  labo- 
ratory in  1906  and  several  hundred  from  similar  shipments  in  1907. 
This  latter  year  no  accurate  records  had  been  made  of  the  number  of 
each  species  of  tachinids  emerging  from  the  importations  of  brown-tail 
moth  material,  but  it  was  known  that  somewhere  between  300  and  500 
individuals  had  been  reared,  the  most  of  which  were  colonized  at  North 
Saugus.  This  was  the  only  lot  of  adult  flies  of  any  consequence  which 
had  been  reared  and  liberated,  and  since  special  efforts  which  had  been 
made  to  recover  this  and  other  species  liberated  at  the  same  time  and 
place  had  failed  in  both  1908  and  1909,  it  was  not  considered  to  be  at 
all  likely  that  the  attempted  colonization  was  successful. 

The  situation,  in  so  far  as  Zygobothria  was  concerned,  could  hardly 
have  appeared  worse  than  it  was  at  the  beginning  of  July,  1910.  No 
one  species  of  anything  like  equal  importance  had  been  quite  so  diffi- 
cult to  secure  in  adequate  numbers  and,  moreover,  there  was  no  imme- 
diate prospect  of  finding  a  way  to  overcome  the  difficulties  attending 
its  importation.  Consequently  no  similar  circumstance,  except  per- 
haps the  recovery  of  the  gipsy-moth  parasite,  Apanteles  fulvipes,  could 
have  caused  a  livelier  satisfaction  than  was  felt  when  several  bona  fide 
specimens  of  Zygobothria  were  reared  from  a  lot  of  cocoons  of  the 
brown-tail  moth  which  had  been  collected  in  the  field  some  time  be- 
fore. The  first  specimen  to  issue  was  a  male  and  it  was  followed  by 
several  more  of  the  same  sex.  The  males  are  markedly  different  from 
the  females  in  appearance  and  not  quite  so  distinctive,  and  we  did  not 
feel  absolutely  sure  of  their  identity  at  first,  but  when  after  a  few  days 
a  female  was  secured  in  the  same  manner  from  American  cocoons 
there  was  no  possible  doubt  that  the  species  was  not  only  established 
in  America  as  firmly  as  three  generations  from  a  small  beginning 
would  permit,  but  dispersing  with  considerable  rapidity,  since  of  the 
seven  specimens  reared  none  was  from  less  than  1  mile  of  the  original 
colony  site  and  one  was  from  at  least  3  miles  distant.  It  is  certain 
that  the  species  must  have  spread  over  at  least  30  square  miles  since 
its  colonization  three  years  ago,  and  when  the  millions  of  brown-tail 
moth  caterpillars  which  are  present  in  that  territory  are  compared 
with  the  few  thousands  which  produced  the  seven  Zygobothria  reared 
in  1910,  it  is  equally  certain  that  its  increase  has  been  at  the  same 
( ime  enormous. 

It  bids  fair,  judging  from  this,  to  do  exceedingly  well  in  America. 
Unlike  ( 1om  psilura  concinnata,  Pales  pavida,  and  other  tachinids,  which 
rank  of  some  import  ance  as  parasites  of  the  brown-tail  moth  and  gipsy 
moth  in  the  Old  World,  il  is  wholly  independent  of  any  host  other 


PARASITES  OF  LARGER  BROWN-TAIL  CATERPILLARS. 


295 


than  the  brown-tail  moth,  and  its  rate  of  multiplication,  being  un- 
questionably more  rapid  than  thai  of  the  brown-tail  moth,  ought  not 
to  be  checked  until  it  has  become  a  factor  in  the  control  of  its  own 
particular  host. 

It  may  be  added  as  a  postscript  that  a  few  days  after  writing  the 
above  a  few  hundred  caterpillars  of  the  brown-tail  moth  collected  in 
the  field  from  hibernating  nests  were  dissected  in  the  laboratory.  Tn 
them  were  found  several  of  the  characteristic  first-stage  Zygobothria 
larva?  (fig.  63,  p.  264)  embedded  in  the  walls  of  the  gullet.  The  evi- 
dence presented  by  this  small  number  of  dissections  is  less  satisfactory 
than  though  the  Dumber  weir  Larger,  but  if  it  is  to  be  accepted  the 
rate  of  increase  of  Zygobothria  in  1 !)  10  is  considerably  better  than  was 
expected. 

PARASITES   ATTACKING  THE    LARGER   CATERPILLARS   OF  THE 

BROWN-TAIL  MOTH. 

II  VM  KNOI'TEIH  >l  S    1 *  \  \l  VSITKS. 

In  Europe  after  the  caterpillars  of  the  brown-tail  moth  resume 
activity  in  the  spring  they  become  Subject  to  attack  by  a  variety  of 
tachinid  parasites,  but  BO  far  as  has  been  determined  by  rearing  work 
with  imported  material  the  only  hymenopterous  parasite  of  any  con- 
sequence is  Meteorus,  which  passes  the  winter  as  a  first-stage  larva  in 
the  hibernating  caterpillars. 

In  fact,  only  a  single  other  parasite  has  ever  been  reared  from 
imported  caterpillars  which  may  not  have  come  from  some  other  acci- 
dentally included  host,  and  this  is  the  Lim  m  riu  m  disparw,  which  has 
already  received  attention  as  a  minor  parasite  of  the  gipsy  moth.  It 
would  certainly  seem  as  though  there  were  likely  to  be  others  attack- 
ing the  caterpillars  of  the  brown-tail  moth  in  Knrope  in  spite  of  the 
fact  that  none  has  been  secured,  and  this  supposition  is  upheld  by  the 
published  results  of  a  study  in  the  parasites  of  the  brown-tail  moth 
which  was  made  a  few  years  ago  by  a  Russian  entomologist,  Mr.  T.  W. 
Emelyanoff.  lie  mentions  a  mi m her  of  parasites  which  have  not  been 
reared  at  the  laboratory  from  imported  material,  and  among  them  one, 
A  pant  el  ex  vitripennis  Hal.,  which  is  so  common,  according  to  his  ac- 
count, that  the  "cocoons  are  sometimes  accumulated  together  in  great 
numbers.  '  Any  suspicions  that  the  Apanteles  thus  observed  by  him 
i->  identical  with  .1.  lacfeicolor  Yier.  as  reared  at  the  laboratory  and 
which  is  the  only  representative  of  the  genus  that  has  been  reared 
from  caterpillars  collected  in  Russia  or  elsewhere,  i>  at  once  dispelled 
by  his  det  ailed  account  of  the  early  life  and  habits  of  the  species  which 
he  had  under  observation  and  which  differ  in  all  essential  par- 
ticulars from  the  life  and  habits  of  A.  lacteicolor.  The  caterpillars 
are  attacked  soon  after  they  leave  the  nests.    Instead  of  dying  in 


296 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


their  molting  webs  they  crawl  down  the  trunks  of  the  trees,  and  the 
cocoons  of  the  parasite  are  found  in  splits  and  holes  in  the  bark,  rarely 
higher  than  from  1  to  1£  yards  from  the  ground.  The  host  caterpillar 
is  left  alive  and  remains  for  some  time  clinging  to  the  cocoons  of  its 
parasite,  something  which  has  never  been  observed  in  the  case  of  A. 
lacteicolor. 

The  plans  for  the  coming  season,  if  they  materialize,  call  for  a  thor- 
ough study  of  the  Russian  parasitic  fauna  of  the  brown-tail  moth,  and 
it  is  sincerely  hoped  that  the  observations  of  Mr.  Emelyanoff  may  be 
confirmed. 

TACHINID  PARASITES. 

Several  of  the  tachinids  which  attack  the  brown-tail  moth  have 
already  been  mentioned  in  the  course  of  the  discussion  of  the  gipsy- 
moth  parasites.  Among  them  Compsilura  concinnata  is  the  only  spe- 
cies which  is  of  real  importance  in  connection  with  both  hosts. 

Tachina  larvarum  is  not  uncommonly  encountered  as  a  brown-tail 
moth  parasite,  but  never  so  commonly  as  it  frequently  is  in  its  other 
connection.  Tricholyga  grandis  has  also  been  reared  in  small  numbers 
from  cocoon  masses  of  the  brown-tail  moth. 

The  tachinid  parasites  of  the  brown-tail  moth,  which  are  either 
unknown  as  parasites  of  the  gipsy  moth  or  which  are  rarely  encoun- 
tered in  that  connection,  include  a  considerable  variety  of  species,  sev- 
eral of  which  appear  to  be  of  little  or  no  real  importance.  As  will  be 
seen,  they  include  amongst  their  number  species  which  represent  the 
extreme  of  diversity  in  habit. 

Dexodes  nigripes  Fall. 

Another  example  of  the  artificiality  of  the  present  accepted  scheme 
of  classification  of  the  tachinid  flies  is  to  be  found  in  the  separated 
positions  therein  occupied  by  the  two  exceedingly  similar  species 
Compsilura  concinnata  and  Dexodes  nigripes.  So  similar  are  these  two 
that  if  a  few  hairs  and  bristles  were  to  be  rubbed  from  the  head  of 
one  it  would  be  practically  impossible  to  distinguish  it  from  the  other, 
even  though  everything  in  connection  with  the  early  stages  and  life  of 
each  was  known.  The  one  point  of  difference  of  any  consequence 
from  an  economist's  standpoint  is  the  more  restricted  host  relation- 
si  lip  of  Dexodes,  which,  though  equally  common  with  Compsilura  as 
a  parasite  of  the  brown-tail  moth  in  Europe,  is  exceedingly  rare  as  a 
parasite  of  the  gipsy-moth  caterpillars.  In  every  other  respect, 
except  host  relationship,  the  habits  of  the  two  are  identical,  and  so  Par 
a-  known  their  earlier  stages  are  absolutely  indistinguishable. 

Dexodes  was  firsl  received  and  liberated  as  a  parasite  of  the  brown- 
t;nl  moth  in  1906,  and  it  was  the  first  of  the  tachinid  parasites  to  be 
cariied  through  all  of  its  transformations  in  the  laboratory  upon  Amer- 


PARASITES  OF  LARGER  BROWN-TAIL  CATERPILLARS.  297 


ican  hosts.  This  was  accomplished  by  Mr.  Titus  in  one  of  the  large 
out-of-door  cages  in  1906,  and  again  with  somewhat  more  success  in  one 
of  the  smaller  indoor  cages  in  1907.  As  with  Compsilura,  only  two 
weeks  are  required  for  the  larval  development,  a  week  or  ten  days  for 
the  pupal  stage,  and  three  or  four  days  for  the  female  to  reach  her 
full  sexual  maturity.  As  is  also  true  with  Compsilura  the  larva?  are 
deposited  by  the  female  beneath  the  skin  of  the  host  caterpillar. 

Several  small  colonies  wrere  planted  by  Mr.  Titus  in  1906,  followed 
by  several  more  small  ones  and  one  larger  one  in  1907.  None  was 
liberated  in  1908,  but  in  1909  one  very  large  and  satisfactory  colony 
was  put  out.  Tn  1910  only  a  single  specimen  of  the  parasite  was 
received  from  abroad  and  this,  curiously  enough,  in  a  shipment  of 
gipsy-moth  caterpillars. 

It  was  confidently  expected  that  in  1910  at  least  a  few  specimens 
would  be  recovered  from  the  held  as  a  result  of  the  earlier  colonization 
work,  but  1  hese  expectations  were  not  realized.  Of  all  of  the  tachinid 
parasites  of  the  brown-tail  moth,  not  excepting  Compsilura  concinnata, 
it  was  the  one  most  satisfactorily  colonized  in  1906  and  1907.  and  on 
♦his  account  it  was  expected  to  find  it  established  in  the  held. 

It  i^  considered  as  one  of  the  most  likely  of  the  as  yet  unrecovered 

parasites  to  be  recovered  from  the  held  in  191 1  or  1912. 

Pakkxokista  chklom.k  Rond. 

No  brown-tail  moth  material  was  received  from  abroad  during  the 
summer  of  100."),  and  consequently  nothing  was  known  of  the  hiber- 
nating tachinids  which  attack  this  host  until  the  spring  of  1907, 
when  they  began  to  issue  from  the  puparia  of  the  previous  summer's 
importations.  All  that  were  reared  that  spring  were  of  the  one 
species,  which  has  since  been  determined  as  Parexorista  clielonix 
Rond..  and  to  date  no  other  species  hibernating  as  a  puparium  and 
with  but  one  annual  generation  has  been  reared  from  this  host. 
Nothing  to  compare  with  the  difficulties  which  attended  the  hiber- 
nation of  the  principal  gipsy-moth  parasite  having  similar  habits 
was  encountered  in  the  case  of  Parexorista.  Its  puparia  (PI.  XX, 
fig.  4)  were  carefully  covered  with  earth  the  first  winter  and  the 
second,  but  it  was  then  found  that  this  precaution  was  unnecessary 
and  that  the  percentage  of  emergence  was  quite  as  large  when  the 
puparia  were  kept  dry  as  when  they  were  damp.  The  difference 
appears  to  be  associated  with  the  state  in  which  the  pupa?  themselves 
hibernate.  Those  of  Blepharipa  and  Orossocosmia  develop  adult 
characters  in  the  fall,  and  it  is  in  reality  the  unissued  adults  which 
hibernate.  Those  of  Parexorista  do  not  develop  adult  characteristics 
until  spring,  and  besides  in  Parexorista  the  space  between  the  pupa 
or  nymph  and  the  shell  of  the  puparium  is  dry  and  does  not,  as  in 
Blepharipa,  contain  a  small  quantity  of  colorless  liquid. 


298 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Accordingly  the  percentage  of  emergence  of  Parexorista  chelonix 
has  aggregated  nearly  or  quite  90  per  cent  each  year  as  against  the 
relatively  small  percentage  of  Blepharipa  which  has  been  carried 
through  its  transformations. 

A  very  few  of  the  flies  were  liberated  in  1907,  but  there  were  too 
few  puparia  of  the  species  received  the  summer  before  to  make  any- 
thing like  a  satisfactory  colony  of  the  species  possible.  In  1908  in 
excess  of  2,000  of  the  flies  issued  from  the  previous  season's  importa- 
tions, and  of  these  about  1,500  were  liberated  in  one  colony  under 
circumstances  which  were  the  most  favorable  that  could  be 
imagined.  The  remaining  ones  were  used  by  Mr.  Townsend  in  a 
successful  series  of  experiments  which  have  already  been  summarized 
in  an  account  of  his  first  year's  work,  published  as  Part  VI  of  Tech- 
nical Series  12  of  the  Bureau  of  Entomology.  Other  equally  satis- 
factory colonies  were  established  later,  but  of  these  nothing  more 
need  be  said  at  this  time. 

The  large  colony  liberated  by  Mr.  Townsend  in  the  spring  of  1908 
consisted  of  flies  of  both  sexes,  very  many  of  which  had  mated  before 
they  were  given  their  freedom.  This  circumstance,  which  was  not 
considered  as  particularly  of  interest  at  the  time,  has  acquired 
significance  more  recently,  as  will  be  shown. 

Later  in  the  spring  and  early  in  the  summer  caterpillars  collected 
from  the  immediate  colony  site  were  found  to  contain  the  larvae  of 
the  parasite,  and  a  calculation  involving  the  number  of  caterpillars 
within  a  limited  area  immediately  surrounding  the  point  of  liberation, 
the  number  of  flies  liberated,  and  the  percentage  of  parasitism  pre- 
vailing in  this  area  indicated  a  very  satisfactory  rate  of  increase.  It 
will  be  remembered  that  the  flies  were  in  part  ready  or  nearly  ready 
to  oviposit  when  they  were  given  their  freedom,  so  that  dispersion  did 
not  have  to  be  taken  into  consideration  to  the  extent  which  is  neces- 
sary when  a  long  period  elapses  between  the  time  of  liberation  and 
the  time  of  recovery. 

In  1909  similar  collections  of  caterpillars  and  cocoons  were  made 
in  the  same  and  in  nearby  localities,  and  the  number  of  Parexorista 
which  was  secured  from  them  was  gratifyingly  large.  These  col- 
lections had  not  been  made  with  the  view  of  determining  the  rate  of 
dispersion,  but  it  was  apparent  that  the  increase  had  been  accom- 
panied by  a  rate  of  dispersion  that  was,  at  the  very  least,  satisfactory 
and  which,  for  all  evidence  to  the  contrary,  might  be  phenomenal. 

Accordingly  in  1910  a  series  of  collections  was  planned,  some  of 
which  were  to  be  made  in  exactly  the  same  localities  as  those  from 
which  the  flies  were  recovered  the  year  before  and  which  were 
designed  to  be  indicative  of  the  prevailing  rate  of  increase,  while 
others  al  varying  distances  and  in  different  directions  from  the  colony 
center  were  designed  to  show  the  rate  of  dispersion.    No  doubt  what- 


PARASITES  OF  LARGER  BROWN-TAIL  CATERPILLARS.  299 


ever  was  felt  concerning  the  recovery  of  the  parasite,  which  was 
considered  to  be  as  firmly  established  as  the  Calosoma  or  Com psi hint 
coiic'innata.  The  results  afforded  another  example  of  the  obtrusive- 
ness  of  the  unexpected.  Not  a  single  Parexorista  puparium  was 
secured  from  any  of  the  material  included  in  this  series  of  collections. 

This  was.  all  things  considered,  the  most  serious  setback  of  any 
which  the  parasite  work  has  experienced  since  its  inception.  It  was 
never  doubted  from  the  first  that  some  among  the  parasites  would 
be  unable  to  exist  in  America,  and  no  species  was  really  credited  with 
having  demonstrated  its  ability  to  do  so  until  it  had  lived  over  at 
least  one  complete  year  out  of  doors.  Parexorista  had  done  this 
and  more,  having  gone  through  two  complete  generations,  unless, 
what  was  not  at  all  likely,  its  puparia  had  all  been  killed  some  time 
during  t he  fall  or  winter. 

Without  indulging  in  unnecessary  speculation  as  to  the  reason  for 
its  disappearance,  the  following  facts  are  presented  for  consideration: 

There  is  in  America  a  tachinid  known  as  Panxor'isfa  c/u  loti'm  , 
which  is  morphologically  identical  with  the  European  race  >o  far  as 

may  be  determined  through  a  painstaking  comparison  of  the  two.  It 
is  a  common  parasite  of  the  tent  caterpillars  Malaeosoma  americcma 

Fab.  and   .1/.  dissfria  Iliibn.     The  adult  Hies  issue  at  the  Bame  time 

in  the  spring  as  do  those  of  the  European  parasite  of  the  brown-tail 
moth.  The  same  type  of  egg  i>  deposited;  the  larva-  are  indistin- 
guishable in  any  of  their  stages  or  habits  during  their  Beveral stages; 
the  third-Stage  Larva  issue  at  the  same  time  and  form  puparia  which 
are  apparently  the  exact  copies  of  the  European,  and  the  hibernating 
habits  are  the  Bame.  The  one  and  only  difference  is  that  the  Ameri- 
can Parexorista  clulonia  does  not  attack  the  caterpillars  of  the1  brown- 
tail  moth,  while  the  European  Parexorista  ehelonia  \<  perhaps  the 
most  important  of  the  tachinid  parasites  of  this  host. 

Mr.  W.  R.  Thompson,  whose  excellent  and  painstaking  work 
makes  possible  the  above  comparison  between  the  two  races,  went 
a  step  further  in  his  investigat ions.  lie  found  by  actual  experiment 
that  iii  confinement,  at  least,  the  European  males  would  unite  with 
the  American  females  with  as  much  freedom  as  with  those  of  their 
own  species.  Granted  that  similar  intermingling  of  the  races  takes 
place  in  the  open,  and  the  reason  for  the  nonrecovery  of  Parexorista 
cheloniae  as  a  parasite  of  the  brown-tail  moth  in  the  summer  of  1910 
is  no  longer  a  mystery. 

It  was  stated  a  lew  paragraphs  back  that  the  flies  which  were  colo- 
nized in  the  spring  of  L908were  largely  mated  at  the  time  of  liberation. 
Their  progeny,  which  issued  in  the  spring  of  1909,  would  therefore  be 
of  the  pure-blooded  European  stock.  Issuing  at  the  same  time  were 
a  vastly  larger  number  of  the  American  race,  because  as  it  happened 
there  was  an  incipient  outbreak  of  Malaeosoma  disstria  in  that  very 


300  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 

locality,  which  was  quite  heavily  parasitized  by  Parexorista.  There 
were  easily  50  or  100  of  the  American  flies  to  one  of  the  European 
race  present  in  that  general  vicinity  in  the  spring  of  1909.  The 
chances  that  the  pure-blooded  European  females  were  fertilized  by 
American  males  were  therefore  a  good  50  or  100  to  1  at  the  most 
conservative  estimate. 

Being  of  the  European  race,  their  instincts  led  them  to  attack  the 
caterpillars  of  the  brown-tail  moth,  and  the  attack  was  successful, 
as  witnessed  by  the  number  of  pup  aria  which  were  secured  from  the 
collected  caterpillars  and  pupse  in  the  summer  of  1909,  but  these 
pup  aria,  instead  of  representing  the  pure-blooded  European  stock,  as 
was  then  supposed,  represented  the  half-breed  stock  resulting  from 
the  promiscuous  mating  of  their  mothers.  Evidently  the  females 
issuing  from  them  in  the  spring  of  1910  lost  the  cunning  which  is 
characteristic  of  the  European  race,  which  makes  possible  the  deposi- 
tion of  the  soft-shelled  eggs  amongst  the  bristling  poisonous  spines 
of  the  host  without  injury. 

Mr.  Thompson,  in  his  experiments  with  the  American  female 
which  had  been  fertilized  by  an  European  male,  found  that  she  was 
neither  anxious  to  oviposit  upon  the  caterpillars  of  the  brown-tail 
moth  nor  able  to  do  this  successfully.  A  proportionately  large 
number  of  the  eggs  deposited  upon  this  host  were  either  pierced  by 
the  poison  spines  or  else  the  young  larvse  came  in  contact  with  these 
and  died  before  entering.  A  few  larvse  did  succeed  in  gaining  en- 
trance, and  one  or  two  passed  through  their  transformations,  but 
when  the  natural  disinclination  to  attack  the  caterpillars  of  the 
brown-tail  moth  was  associated  with  a  heavy  mortality  following 
occasional  attack  the  percentage  of  parasitism  is  reduced  to  the 
minimum. 

Tn  consequence  of  these  observations  in  field  and  laboratory,  the 
name  of  Parexorista  chelonise  has  been  erased  from  the  list  of  promis- 
ing European  parasites  of  the  brown-tail  moth  and  placed  at  the  head 
of  the  list  of  the  imported  parasites  which  are  proved  unfit. 

Tt  is  a  pity,  too,  as  has  incidentally  been  stated,  because  it  is  about 
the  most  common  of  any  of  the  tachinid  parasites  in  Europe,  and, 
moreover,  is  one  which  is  entirely  independent  of  any  alternate  host. 

Pales  pavida  Meig. 

There  is  a  very  considerable  group  of  tachinid  parasites  of  the 
brown-tail  moth  which  appears  to  be  more  commonly  encountered  in 
material  from  southern  European  localities  than  from  those  in  the 
north.  One  of  these,  Zygobothria  nidicola,  has  already  been  the 
subject  of  lengthy  discussion.  The  fact  that  though  apparently 
southern  in  its  distribution  in  Europe,  it  has  manifested  a  strong 
tendency  to  become  thoroughly  acclimatized  here,  has  lent  encour- 


PARASITES  OF  LARGER  BROWN-TAIL  CATERPILLARS.  301 


agemenl  to  the  attempts  which  have  been  made,  and  which  will  be 
renewed,  looking  toward  the  establishment  here  of  others  havim:  a 
somewhat  similar  distribution. 

Pales  pavida  (fig.  70)  is  perhaps  as  promising  as  any  among  these, 
although  it  is  possible  that  it  appears  so  on  account  of  a  somewhat 
larger  knowledge  which  we  possess  concerning  its  life  and  habits.  It 
was  firsl  imported  in  not  very  Large  numbers  in  L906.  In  1 907  about 
as  many  were  secured  and  colonized  as  of  the  successfully  introduced 
Zygobothria,  and  more  were  colonized  in  1909.  The  fact  that  it 
has  not  been  recovered  is  by  no  means  to  be  taken  as  positive  asssur- 
ance  that  it  is  not  established,  and  it  is  well  within  the  bounds  of 
possibility  that  it  will  he  recovered  in  1911  or  1912. 

It  is  one  of  the  species 
which  deposits  its  eggs 

upon  the  leaves  to  be 
eaten  by  its  host  (fig.  36, 
p.  214)  and  was  t  he  first 
species  having  this  habit 
to  be  carried  through  all 
of  its  transformations  in 
the  laboratory.  In  190S 
Mr.  Townsend  succeeded 
in  carrying  some  of  the 
flies  through  the  period 
allotted  h>i-  the  incuba- 
tion of  their  eggs,  but  he 
did  not  succeed  in  secur- 
ing oviposition.  In  1 909 
Mr.  Thompson  had  better 
fortune,  and  not  only  se- 
cured eggs  in  abundance, 
but  fed  these  eggs  to  a  variety  of  caterpillars  and  secured  either  the 
puparium  or  the  fly  in  nearly  every  instance,  lie  also  secured  much 
interesting  data  upon  the  early  stages,  and  upon  the  life  and  habits 
of  the  early  stages,  a  story  of  which  is  left  for  him  to  tell.  The 
accompanying  illustrations  of  the  eggs  and  larva1  were  prepared 
under  his  direction.  That  of  the  egg  (fig.  37,  t>.  p.  214)  is  of  inter- 
est in  comparison  with  that  of  the  egg  of  Blepharipa  scutellata  (fig. 
37,  a,  p.  21  I),  as  showing  the  difference  in  the  characteristic  micro- 
scopic markings.  That  of  the  larva  will  give  a  good  idea  of  the 
integumental  "funnel"  (figs.  71,  72),  formed  by  the  ingrowing  epi- 
dermis, as  differing  from  the  tracheal  "funnel"  characteristic  of  the 
Larva  of  Blepharipa,  as  figured  on  pages  215  and  216. 


Fig.  lO.—Palts  pavida:  Adult  femal>»,  with  front  view  of  head 
above  and  side  view  below,  and  antenna  at  left.  Much  en- 
ttbttged.  (Original.) 


302 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


Fig.  71.— Pales  pavida:  Second-stage  larva  in  situ  in 
basal  i)ortion  of  integumental  "funnel."  Much  en- 
larged. (Original.) 


Not  very  much  that  is  definite  can  be  said  of  the  seasonal  history 
of  Pales.  It  undoubtedly  will  require  another  host  than  the  cater- 
pillar of  the  brown-tail  moth  in 
order  that  it  may  complete  its 
seasonal  cycle,  but  that  it  will 
find  such  a  host  is  pretty  cer- 
tain. It  would  rather  appear, 
from  what  has  been  observed, 
that  it  will  attempt  to  hibernate 
as  an  adult.  Whether  or  not  it 
will  be  able  successfully  to  do 
this  in  New  England  remains  to 
be  proved. 

It  has  occasionally  been  reared 
as  a  parasite  of  the  gipsy  moth, 
and  if  successfully  introduced 
into  America  it  ought  to  be  of 
some  assistance  in  this  role  also. 
Unfortunately,  as  a  parasite  of 
the  caterpillar  of  the  brown-tail 
moth,  it  does  not  issue  until 
about  the  time  when  the  moth 
would  have  issued  had  the  individual  remained  healthy.  It  requires 
some  little  time  for  the  females  to  develop  their  eggs,  and  it  is  not 
at  all  likely  that,  like  Compsilura,  it  will  be  found  to  pass  one  genera- 
tion upon  the  caterpillars  of  the 
brown-tail  moth,  and  the  next 
upon  the  gipsy-moth  caterpil- 
lars. 


Zenillia  libatrix  Panz. 

This  parasite,  like  Pales,  de- 
posits its  eggs  upon  foliage  to 
be  eaten  by  its  host,  but,  unlike 
Pales,  it  has  not  been  reared 
through  its  stages  in  the  labo- 
ra  t  ory.  Like  Pales,  it  is  south- 
ern in  its  distribution,  and  in 
relative  importance  they  are 
about  equal,  judging  from  the 
numbers  of  each  which  have 
been  reared  at  the  laboratory. 

It  was  colonized  in  small 
numbers  in  1900,  in  larger  numbers  in  1907,  and  in  very  small  num- 
The  circumstances  attending  its  colonization  are 


Fig.  72. — Pales  pavida:  Integumental 
ing  orifice  in  skin  of  host  caterpillar. 
(Original.) 


funnel,"  show.- 
Much  enlarged. 


bers  subsequently. 


PARASITES  OF  LARGER  BROWN-TAIL  CATERPILLARS.  303 


Flo.  IZ.—Kudoromyia  magmcnrnis:  Adult  female,  with  front  and  side 
\  lewi  of  head  at  right .    Much  enlarged.  (Original.) 


as  satisfactory,  so  far  as  known,  as  those  attending  the  colonization 
of  Pales  and  Zygo- 
bothria,  and  it  is 
hoped  that  it  may  be 
recovered  in  the 
course  of  1911  or 
1912.  It  is  also 
hoped  that  a  large 
number  will  be  im- 
ported in  1911. 

Masicera  sylvatica 
Fall. 

This  tachinid  ap- 
pears not  to  be  un- 
common as  a  parasite 
of  the  brown-tail 
moth  in  Italy,  hut 
has  not  been  received 
from  other  countries 
in  more  than  I  lie  mos4 
insignificant  num- 
bers. Not  enough  have  been  received  to  make  anything  like  colo- 
nization possible,  and  it  is  one  of  the  species  which  it  is  hoped  to 

receive  in  1911. 


KlDOHO.MVIA    MACMIOHMS  ZkTT. 


This  (see  lig.  73)  is  the  most  distinc- 
tive  of  the  tachinid  flies  parasitic  upon 
the  brown-tail  moth,  and  the  only  one 
among  t  he  parasites  of  either  t  he  gipsy 
moth  or  the  brown-tail  moth  w  hich  has 
the  habit  of  depositing  its  active  larvaa 
upon  the  food-plant  of  its  host.  This 
habit  was  first  discovered  by  Mr. 
Townsend,  who  gives  an  account  of 
the  manner  of  the  discovery  in  Techni- 
cal Series  VI,  part  12,  of  this  bureau, 
from  which  the  accompanying  figure 
(fig.  74)  was  taken. 

It  is  another  of  the  group  of  tachinid 
parasites  which  appear  to  be  southern 
rather  than  northern  in  distribution, 
on  account  of  which  it  has  been  found 
impossible  to  secure  a  sufficient  number  to  make  adequate  colonies 


Fig.  74.— Eudoromyia  magnicornis:  a,  First- 
stage  maggot  attached  to  leaf,  awaiting 
approach  of  a  caterpillar;  6,  mouth-hook 
of  maggot,  o,  Greatly  enlarged;  b,  highly 
magnified.   (From  To\vns?nd.) 


304  PARASITES  OF  GIPSY  AND  BROWN -TAIL  MOTHS. 

practicable.  It  was  colonized  together  with  Zygobothria  nidicola, 
Pales  pavida,  and  Zenillia  libatrix,  in  about  the  same  numbers  in 
1906  and  1907,  and,  like  the  two  last  named,  it  is  hoped  to  recover 
it  in  1911.  It  is  also  hoped  to  import  and  liberate  a  much  larger 
number  than  hitherto  during  that  year. 

Cyclotophrys  anser  Towns. 

Mr.  Townsend  described  this  species  as  new  from  specimens  reared 
in  1908  from  brown-tail  moth  material  received  from  the  Crimea. 
It  has  not  been  detected  in  shipments  of  similar  character  from  any 
other  locality  in  sufficient  numbers  to  indicate  it  as  being  an  important 
parasite,  nor  have  enough  been  received  from  the  Crimea  to  make 
possible  its  colonization.  It  is  hoped  that  this  may  be  done  in  the 
course  of  the  year  1911. 

It  is  one  of  the  relatively  few  species  of  tachinids  attacking  the 
larvae  of  the  brown-tail  moth  which  deposit  large,  flattened  eggs 
upon  the  body  of  the  host  caterpillars. 

Blepharidea  vulgaris  Fall. 

This  is  almost  the  only  tachinid  parasite  of  either  the  gipsy  moth 
or  the  brown-tail  moth  which  is  of  no  apparent  importance  in  con- 
nection with  either  host  and  which  at  the  same  time  has  been  reared 
a  sufficient  number  of  times  to  make  its  host  relationship  reasonably 
certain.  The  few  specimens  which  have  been  received  have  mostly 
come  from  various  parts  of  the  German  Empire.  Very  little  is 
known  of  its  life  and  habits,  and  it  is  not  considered  as  being  of 
sufficient  importance  to  warrant  further  investigation. 

PARASITES  OF  THE  PTJPjE  OF  THE  BROWN-TAIL  MOTH. 

By  far  the  most  important  of  the  parasites  of  the  pupae  of  the 
brown-tail  moth  in  Europe  appears  to  be  Monodontomerus,  an  account 
of  which  has  already  been  given  in  the  discussion  of  the  parasites  of 
the  gipsy  moth.  It  is  more  frequently  reared  in  connection  with  the 
brown-tail  moth  than  with  the  gipsy  moth,  and  some  of  the  ship- 
ments of  cocoons  have  produced  it  in  extraordinary  numbers. 

Theronia,  also  mentioned  as  a  parasite  of  the  gipsy  moth,  is  about 
the  next  in  importance,  but  the  European  T.  atalantx  Poda  is  no 
more  frequently  reared  than  the  American  T.  fulvescens  Cress. 

The  same  species  of  Pimpla  already  mentioned  as  parasites  of  the 
gipsy  moth  in  Europe  attack  the  brown-tail  moth  as  well.  Like 
Theronia  and  Monodontomerus,  they  are  more  frequently  encountered 
in  this  connection  than  in  the  other. 

No  species  of  Chalcis  has  been  reared  from  any  European  material 
received  to  date,  and  in  this  respect  the  parasitism  of  the  pupa  of 


BUM  MARY  AND  CONCLUSIONS. 


305 


the  brown-tail  moth  differs  from  that  of  the  gipsy  moth.  It  further 
dhTers  in  that  two  small  gregarious  chalcidids,  both  of  them  closely 
allied  or  identical  with  American  species  of  the  same  respective 
genera,  have  occasionally  been  reared  from  imported  cocoon  masses. 
Neither  of  these  is  common.  One,  Diglochis  omnivora  Walk,  appears 
to  be  specifically  indistinguishable  from  the  form  which  goes  under 
the  same  name  in  America,  where  it  lias  occasionally  been  reared 
from  the  gipsy  moth  and  abundantly  from  the  brown-tail  moth. 
The  other  is  a  species  of  Pteromalus,  winch,  according  to  Mr.  Craw- 
ford, is  hardly  to  be  distinguished  from  the  tussock-moth  parasite, 
Pteromalus  cuproideus  I  low. 

Enough  of  the  latter  species  have  been  reared  to  make  small 
colonies  possible,  but  these  colonies  have  been  so  very  small  as  to 
make  its  establishment  improbable.  It  is  hoped  that  a  larger 
number  will  be  imported  in  191  I,  but  since  it  appears  to  be  of  very 
slight  importance  in  Europe  no  great  enthusiasm  is  felt  over  the 
prospect. 

SUMMARY  AND  CONCLUSIONS. 

The  work  of  introducing  into  America  the  parasites  and  other 
natural  enemies  of  the  gipsy  moth  and  the  brown-tail  moth  has  been 
more  arduous  than  was  anticipated  when  it  was  begun.  It  was  soon 
found  that  the  published  information  concerning  these  enemies  was 
deficient  and  unreliable,  and  that  much  original  research  was  neces- 
sary in  order  that  they  might  be  intelligently  handled.  Later  it 
developed  that  the  rate  of  dispersion  of  the  introduced  species  was 
so  very  rapid  as  to  necessitate  larger  and  stronger  colonies  than  had 
been  contemplated. 

The  policy  originally  adopted  of  employing  foreign  entomologists 
to  collect  the  eggs,  caterpillars,  and  pupa;  of  these  pests  abroad  for 
shipment  to  the  Massachusetts  laboratory,  where  the  parasites 
which  they  contained  might  be  reared,  has  resulted  in  the  successful 
importation  and  colonization  of  a  considerable  number  of  the  para- 
sites which  a  study  of  this  material,  after  its  receipt  at  the  laboratory, 
has  indicated  as  being  of  importance.  Numerous  others  success- 
fully imported  have  been  colonized,  but  so  recently  as  to  render  the 
success  of  the  experiment  uncertain.  On  account  of  the  rapidity 
of  dispersion,  which  results  in  the  parasites  being  very  rare  over  a 
large  territory  instead  of  being  common  over  a  restricted  territory, 
as  long  a  period  as  four  years  may  elapse  before  it  is  possible  to  recover 
them  after  colonization.  It  has  been  found  impossible  to  secure  cer- 
tain of  the  parasites  in  adequate  numbers  for  colonization  under  satis- 
factory conditions.  The  proportion  of  such  is  very  small,  it  is  true, 
but  at  the  same  time  it  may  easily  be  that  ultimate  success  or  failure 

1)5077°— Bull.  91—11  20 


306  PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


may  depend  upon  the  establishment,  not  of  the  most  important 
among  the  parasites  and  other  natural  enemies,  but  of  a  group  or 
sequence  of  species  winch  will  work  together  harmoniously  toward 
the  common  end.  Viewed  in  this  light,  the  importance  of  parasites 
which  otherwise  might  be  considered  as  of  minor  interest  is  greatly 
enhanced. 

It  is  impracticable  to  determine  certain  facts  in  the  life  and  habits 
of  those  parasites  which  have  been  colonized  under  conditions 
believed  but  not  known  to  be  satisfactory.  Further  detailed  knowl- 
edge is  necessary  before  we  can  judge  whether  the  circumstances  sur- 
rounding colonization  were  in  truth  the  best  that  could  be  devised. 
Furthermore,  so  long  as  original  research  is  confined  to  the  study  of 
materia]  collected  by  foreign  agents,  some  of  whom  are  technically 
untrained,  it  is  practically  impossible  to  secure  the  evidence  necessary 
to  refute  published  statements  concerning  the  importance  of  certain 
parasites  abroad  which  the  results  of  first-hand  investigations  have 
not  served  to  confirm.  It  is  believed  that  these  statements  are 
largely  based  upon  false  premises,  but  should  this  belief  prove  un- 
grounded it  would  mean  that  there  are  important  parasites  abroad 
of  which  little  or  nothing  is  known  first-hand. 

A  determined  effort  was  made  in  1910  to  better  the  deficiencies  in 
the  foreign  service  without  going  to  the  lengths  of  adopting  a  radically 
changed  policy,  but  the  results  were  not  satisfactory.  Lack  of 
assurance  that  a  continuation  of  the  work  in  1911  along  similar  lines 
would  bring  more  favorable  results  made  its  continuation  inadvisable. 
It  therefore  became  a  question  of  adopting  new  and  radically  different 
methods  in  so  far  as  the  foreign  service  was  concerned. 

In  favor  of  a  policy  of  inactivity  was  the  prospect  of  an  imme- 
diate reduction,  as  opposed  to  an  increase,  in  expenditures  should 
renewed  activity  be  decided  upon.  There  was  the  chance  that  the 
parasites  already  introduced  and  colonized  would  be  sufficient  to 
meet  the  demands  of  the  situation. 

On  the  other  hand,  the  vast  majority  of  defoliating  native  insects, 
which  rarely  or  never  become  so  abundant  as  to  be  considered  injuri- 
ous, prove  upon  investigation  to  support  a  parasitic  fauna  similar 
in  all  its  essential  characteristics  to  that  supported  by  the  gipsy 
moth  in  countries  where  it  is  similarly  a  pest  at  very  rare  intervals 
or  not  at  all. 

Parasitism  appears  to  be  unique  among  the  many  factors  of  con- 
trol, in  that  no  other  agency  similarly  increases  in  efficiency  in  direct 
proportion  as  the  efficiency  of  other  agencies,  such  as  climatic  con- 
ditions, miscellaneous  predators,  etc.,  diminishes.  In  short,  the 
apparent  importance  of  parasitism  as  a  factor  in  the  natural  control 
of  defoliating  insects  has  been  decided!}  enhanced  as  a  result  of 
these  more  or  less  technical  and  intensive  studies.    It  can  be  said 


PRESENT  STATUS  OF  INTRODUCED  PARASITES. 


307 


with  the  utmost  assurance  that  if  a  sufficient  number  and  variety  of 
parasites  and  other  natural  enemies  of  the  gipsy  moth  which  act  in  a 
manner  comparable  to  the  true  facultative  parasites,  as  above  de- 
scribed, can  be  introduced  into  America,  the  automatic  control  of 
the  gipsy  moth  will  be  permanently  effected. 

During  the  past  four  years  the  "wilt"  disease  has  been  increasing 
somewhat  in  efficiency,  but  notwithstanding  that  it  is  and  has  been 
prevalent  in  every  locality  in  which  the  gipsy  moth  has  been  allowed 
to  increase  unchecked,  the  gipsy  moth  still  continues  to  be  a  menace 
to  the  life  and  health  of  valuable  trees  which  have  been  protected 
during  this  time  at  a  considerable  cost.  In  parts  ol  Russia,  where 
parasitic  control  is  obviously  inefficient,  control  through  disease  is 
not  sufficient  to  keep  the  gipsy  moth  from  increasing  until  defoliation 
of  huge  areas  results.  Similarly,  in  America,  the  destruction  of  very 
large  numbers  of  caterpillars  of  several  sorts  of  the  larger  Lepidoptera 
has  been  observed,  but  in  no  instance  until  after  the  caterpillars 
involved  had  increased  to  such  numbers  as  to  become  a  pest. 

It  may  be  that  the  parasites  already  introduced  and  established, 

Or  likely  to  become  established,  will  prove  to  be  Milhcient  for  the 

purposes  intended.  Only  events  themselves  can  be  depended  upon 
to  answer  this  question,  ami  from  five  to  six  years  must  pass  before 
the  answer  is  known.  During  this  period  the  gipsy  moth  will  con- 
tinue to  disperse  and  multiply,  and  large  expenditures  will  be  neces- 
sary to  prevent  much  more  rapid  dispersion  and  multiplication  than 
has  prevailed  in  t  he  past . 

Ivxpenditures  amounting  to  a  very  small  percentage  of  the  total 
will  suffice  to  carry  on  the  parasite  work.  If  the  parasites  already 
introduced  are  sullicient  to  meet  the  needs  of  the  situation,  the 
expenditure  projected  will  have  been  needless  and  unnecessary.  If 
the  parasites  already  introduced  are  not  sullicient.  it  may  be  that 
this  deficiency  can  be  made  up  in  time  to  avoid  much  if  any  delay 
in  the  day  of  final  triumph. 

THE  PRESENT  STATUS  OF  THE  INTRODUCED  PARASITES. 

PARASITES  OF  THE  GIPSY  MOTH. 
EGG  PARASITES. 

Anastatus  bifasciatus  Fonse. 

Received  first  in  1908.  Colonized  unsuccessfully  in  1908  and  successfully  in  1909. 
First  recovered  in  immediate  vicinity  of  Colony  in  1  !»<)!).  Increased  notably  in  MHO, 
but  indicated  dispersion  is  only  about  250  feet  per  year.  Artificial  dispersion  neces- 
sary.   Apparently  well  established. 

SCHED1US  KUVANiE  HOW. 

Received  first  in  1907,  dead,  and  in  1909,  living.  Successfully  colonized  in  1909. 
Recovered  in  immediate  vicinity  of  colony  site  in  1909.  Doubtfully  recovered  in 
1910.    Establishment  very  doubtful  on  account  of  climatic  conditions. 


308 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


HYMENOPTEROUS  PARASITES  OF  CATERPILLARS. 

Apanteles  fulvipes  Hal. 

Received  first  in  1905,  dead,  and  in  1908,  living.  Colonized  unsatisfactorily  in 
1908  and  under  exceptionally  favorable  conditions  in  1909.  Two  generations  recovered 
in  immediate  vicinity  of  colony  site  in  1909.  Not  recovered  in  1910  except  from 
recent  colony.    Establishment  doubtful  on  account  of  lack  of  proper  alternate  hosts. 

TACHINID  PARASITES. 

COMPSILURA  CONCINNATA  Meig. 

First  received  in  1906  and  colonized  same  year.    Colony  strengthened  in  1907. 
Recovered  doubtfully  in  1907  from  immediate  vicinity  of  a  colony  site.  Certainly 
recovered  and  found  to  be  generally  distributed  over  considerable  territory  in  1909. 
Marked  increase  in  1910.    Apparently  established. 
Carcelia  gnava  Meig. 

Doubtfully  colonized  in  1906.    Satisfactorily  colonized  in  1909.    Not  recovered 
from  field.    Establishment  hoped  for. 
Zygobothria  gilva  Hartig. 

Doubtfully  colonized  in  1906.    Satisfactorily  colonized  in  1909.    Not  recovered 
from  field.    Establishment  hoped  for. 
Tachina  larvarum  L. 

First  received  in  1905  and  colonized  in  1906.    Much  more  satisfactorily  in  1909. 
Not  recovered.    Establishment  doubtful  on  account  of  hybridization  with  similar 
American  species. 
Tachina  japonica  Towns. 

First  received  and  poorly  colonized  in  1908.    A  better  colony  put  out  in  1910. 
Recovery  doubtful  on  same  account  as  above. 
Tricholyga  grandis  Zett. 

Doubtfully  received  and  colonized  in  1906.    Satisfactorily  colonized  in  1909. 
Recovered  from  immediate  vicinity  of  colony  site  in  1909.    Not  recovered  in  1910, 
but  establishment  hoped  for. 
Parasetigena  segregata  Rond. 

First  received  in  1907  and  colonized  in  1910.    Not  recovered.  Establishment 
hoped  for  and  expected. 
Blepharipa  scutellata  R.  D. 

First  received  in  1905.    Colonized  under  very  unsatisfactory  conditions  in  1907. 
Satisfactory  colonization  for  first  time  in  1909.    Recovered  from  immediate  vicinity 
of  colony  site  in  1910.    Establishment  confidently  expected. 
Crossocosmia  spp. 

First  received  in  1908  and  colonized  in  1910  under  fairly  satisfactory  conditions. 
Not  recovered.    Establishment  rather  doubtful  on  account  of  unsatisfactory  colony. 

PARASITES  OF  THE  PUPA. 

Monodontomerus  jEreus  Walk. 

First  received  in  1906.  Colonized  in  1906.  Recovered,  generally  distributed  over 
considerable  area,  in  winter  of  1908-9.  Firmly  established  and  dispersing  at  a  very 
rapid  rate. 

PrMPLA  spp.    (See  Parasites  of  the  brown-tail  moth.) 
Chalcis  obscurata  Walk. 

First  received  ill  1908.  Colonized  in  1908  and  1909,  but  not  satisfactorily.  Estab- 
lishment doubtful  on  account  of  small  size  of  colony. 


PRESENT  STATUS  OE  INTRODUCED  PARASITES. 


309 


Chalcis  flavipes  Panz. 

First  received  in  1905.  Colonized  in  1908  and  1909  but  in  unsatisfactory  numbers. 
Recovered  from  immediate  vicinity  of  colony  site  in  1909.  Not  recovered  in  1910. 
Establishment  doubtful  on  account  of  small  colony. 

PREDACEOUS  BEETLES. 

Caosoma  sycophant a  L. 

First  received  in  1906.  Colonized  same  year.  Recovered  from  immediate  vicinity 
of  colony  sits;  in  1907.  Found  generally  distributed  over  limited  area  in  1909.  Firmly 
established  and  increasing  and  dispersing  rapidly. 

PARASITES  OF  T11F  BROWX-TAIL  MOTH. 
PARASITES  OF  THE  EGG. 

TliK  IIOfiRAMMA  Spp. 

Fir^t  received  in  1900.  Colonized  in  1907;  more  satisfactorily  in  1909.  Recovered 
from  immediate  vicinity  of  colony  site  in  1909.  Not  recovered  in  1910.  Establish- 
ment probable,  but  the  species  of  no  importance  as  a  parasite. 

TeLKNOMI  S  I'HALSN'ARUM  NeeS. 

First  received  in  1906  and  colonized  satisfactorily  in  1907.  No  attempts  toward 
recovery  since  made.    Establishment  hoped  for.    Not  an  important  parasite. 

PARASITES   ATTACKING   HIBERNATING  CATERPILLARS. 

Ptekom Al.i  s  BGRXGIUS  I'orsl. 

Received  first  in  l!>0li.    Colonized  in  lari^e  numbers  that  year  and  in  1907  but  much 
more  satisfactorily  in  1 90S.    Recovered  from  immediate  vicinit  y  of  colony  site  in  1909. 
Not  recovered  in  1910.     I'miml  to  1"'  generally  distributed  over  very  extended  terri- 
tory in  1911. 1    Apparently  well  established. 
Apanteles  lactkk  OI.OK  \ 'ier. 

Received  first  in  1906.    Colonized  in  1907.    Satisfactorily  colonized  in  1908.  Re- 
covered in  immediate  vicinity  of  colony  site  in  1909.    (ionerally  distributed  over 
considerable  area  in  1910.    Apparently  firmly  established. 
Meteorus  VERSICOLOR  Wesin. 

First  received  in  L906.    Colonized  satisfactorily  in  1908.    Recovered  in  immediate 
vicinity  of  colony  site  in  1909.    Generally  distributed  over  limited  area  in  1910. 
Apparently  firndy  established. 
Zyoohothria  nidicola  Towns. 

First  received  in  1900.  Colonized  unsatisfactorily  only  in  1906-7,  but  notwith- 
standing was  recovered  in  1910  over  a  considerable  territory.  Apparently  firmly 
established. 

TACHINID  PARASITES  OF  LARGER  CATERPILLARS . 

Compsilura  concinnata  Meig.    (See  Gipsy-moth  Parasites.) 
Tachina  larvarum  L.    (See  Gipsy-moth  Parasites.) 
Dexodes  nigripes  Fall. 

First  received  in  1900  and  colonized  satisfactorily  in  1906  and  1907.  Still  more 
satisfactorily  colonized  in  1909.    Not  recovered.    Establishment  hoped  for. 

EUDOROMYIA  MAGNICORNIS  Zett. 

First  received  in  1906.  Colonized  in  about  the  same  numbers  as  Zygobothria  nidicola 
in  1906  and  1907.  Not  recovered.  Establishment  doubtful  on  account  of  small  size 
of  colonies. 

i  Winter  of  1910-11. 


310 


PARASITES  OF  GIPSY  AXD  BROWX-TAIL  MOTHS. 


Pales  pavida  Meig. 

Status  same  as  that  of  Eudoromyia. 
Parexorista  cheloxl*:  Rond. 

Received  first  in  1906.  Colonized  very  unsatisfactorily  in  1907  and  satisfactorily  in 
1908.  Recovered  in  immediate  vicinity  of  colony  site  in  1908  and  in  larger  numbers 
in  1909.  Not  recovered  in  1910.  Establishment  very  doubtful  on  account  of  hybridi- 
zation with  American  race. 


PARASITES  OF  THE  PUP^E. 

Pimpla  examixator  Fab. 

PlMPLA  IXSTIGATOR  Fab. 

First  received  in  1906  and  colonized  in  1906  and  1907  unsatisfactorily.  Establish- 
ment doubtful.  Of  better  promise  as  parasites  on  account  of  great  similarity  to 
American  species. 

Moxodoxtomerus  ^reus  Walk.    (See  Gipsy -moth  Parasites.) 

The  gross  number  of  each  of  the  various  species  which  have  been 
colonized  since  the  beginning  of  the  work  up  to  and  including  the 
season  of  1910  is  given  in  the  accompanying  tabulated  statement: 

Tachinid  Parasite.. — Con. 


Hymenopterous  Parasites. 

Schedius  kuvanx  How.  ...  1,  061,  111 
3  P  te  romalus  egregius 

Forst   354,  300 

AnastatusbifasciatusYonsc.  177, 210 

Trick ogramma  s p p   76,000 

Apanteles  fulvipes  Hal   57,  700 

Apanteles  lacteicolor  Vier.  44,310 
Monodontomerus  aereus 

Walk   15,325 

Telenornus  phalxnarum 

Nees   4,650 

Meteorus  versicolor  Wesm.  3, 113 

Pimpla  spp   583 

Chalcisspv   338 


[,  640 


Tachinid  Parasites. 

Carcelia  gnava  Meig  

2  Trichobjga  grandis  Zett. . 
2  Zygobothria  gilva  Hartig. 
2  Compsilura  concinnata 

Meig  

2  Dexodes  nigripes  Fall .... 
2  Blepharipa  scutellata 

R.  D  

Parexorista  chelonix  Rond . 
2  Tachina  lar varum  L  


Parasetigena  scgregata 

Rond  

4  Crossocosmia  sericarix 

Corn  

2  Pales  pavida  Meig  

Tachina  japonica  Towns.  . 

2  Zenillia  Ubatrix  Panz  

2  Zygobothria  nidicola 

Towns  

Masicera  silvatica  Fa'l  

2  Eudoromyia  magnicornis 

Zett  

1  Unclassified  t  a  c  h  i  n  i  d  s 

(1906-07)  


1,187 

699 
476 
471 
161 

109 

23 


9.420 


68,  343 


Predatory  beetles. 
15,  581  Calosoma  sycophanta  L.  . .       17,  742 

Carabus  auratus  L   478 

Calosoma  inquisitor  L   262 

Carabus  arvensis  Hbst   108 

Carabus  nemoralis  Mull. . .  100 

Calosoma  rcticulatum  Fab.  83 

Carabus  violaceus  I>   62 


8,721 
7,  502 

6,  777 
5,  040 


5, 109 
5,  026 
2,  036 


i  s.  s:;5 


Total  «...  1,881,818 


1  Including  species  marked  (2). 

2  Species  which  are  also  included  under  "unclassified  tachinids." 

3  Does  not  include  progeny  of  114,000  individuals  liberated  in  1908. 
*  Including  also  C.  JlavoscuUllata. 


DEVELOPMENTS  OF  YEAR  1010. 


311 


THE  DEVELOPMENTS  OF  THE  YEAR  1910. 

At  the  beginning  of  the  year  1910  the  statement  was  made  that  if 
the  parasites  maintained  the  rate  of  progress  which  was  then  indi- 
cated by  the  results  of  the  recent  field  work,  the  year  1916  would  see 
the  triumphant  conclusion  of  the  experiment  and  the  automatic  con- 
trol of  the  giperj  moth  through  parasitism.  This  prophecy  was  also 
dependent  upon  the  measurable  success  of  the  importation  work 
which  was  planned  for  1910. 

The  importations  of  1910  were  disappointing,  and  did  not  result  in 
the  colon i/.at ion  of  the  few  parasites  which  have  not  yet  been  liberated 
in  America,  under  satisfactory  conditions.  Neither  has  the  progress 
of  the  parasites  in  the  field  been  quite  as  satisfactory  as  was  hoped 

and  expected. 

The  failure  of  Schedius   to  demonstrate  as  clearly  as  might  be 

wished  its  ability  to  Burvive  the  winter  was  the  first  unfavorable 
development  in  1910.  Recovery  of  Aj>aitt<hs  fu/ripts,  while  not 
expected,  was  hoped  for,  and  although  its  nonrecovery  can  not  be 
considered  as  surely  indicative  of  its  inability  to  establish  itself  here, 
it  is  none  the  Less  disquieting.  Discovery  of  the  error  in  identity 
which  had  resulted  in  misapprehensions  concerning  the  status  of 

Tr'ichol 'i/ffa  <}i<iutl'is  was  ;i  serious  blow  to  expectations  concerning  the 
future  of  this  species.  Most  serious  of  all  was  the  nonrecovery  of  the 
important  brown-tail  moth  parasite,  Parexorista  chelonise,  which  was 
considered  to  be  thoroughly  well  established  at  the  close  of  the  sea- 
son of  1909,  Similarly,  the  failure  of  Monodotomerus  to  increase  in 
efficiency  to  the  extent  which  was  expected,  was  viewed  with  appre- 
hension, as  possibly  indicative  of  what  might  result  with  others  of 
the  imported  species. 

To  offset  these  several  and  various  reverses  was  the  unexpectedly 
satisfactory  increase  in  abundance  and  dispersion  of  Oalosoma. 
Anastatus  did  better  than  was  expected  in  the  matter  of  increase  in 
numbers  and  in  effect  iveness  and  slightly  better  in  dispersion.  Bleph- 
aripa  w  is  recovered,  w  hen  recovery  was  not  expected  so  soon  follow- 
ing its  liberation,  and  Compsilura  was  considerably  more  abundant, 
and  promised  more  efficient  assistance  than  h  ul  been  hoped  for. 
Among  the  brown-tail  moth  parasites,  Apanteles  gave  evidences 
of  a  more  rapid  increase  and  wider  dispersion  than  was  expected, 
and  Meteorus  was  also  unexpectedly  abundant  over  a  limited  area, 
and  later  showed  evidence  of  rapid  dispersion.  The  recovery  of 
Zi/gohotJnia  nidicola,  after  its  disappearance  for  two  or  three  years, 
was  the  most  satisfactory  and  unexpected  of  the  favorable  results  of 
the  season's  field  work  until  the  recovery  of  PteTomalus  in  the  fall 
and  during  the  winter.  Although  this  latter  is  not  an  important 
parasite,  its  nonestablishment  was  practically  conceded,  and  the 


312 


PARASITES  OF  GIPSY  AND  BROWN-TAIL  MOTHS. 


circumstances  surrounding  its  recovery  are  considered  to  be  highly 
gratifying  and  significant. 

It  is  by  no  means  easy  to  draw  a  balance  which  should  fairly 
represent  the  status  of  the  work  as  a  whole  in  1910  as  compared 
with  1909,  but  after  long  consideration  it  was  definitely  decided  that 
the  present  status  of  the  parasites  was  perhaps  less  favorable  to  ulti- 
mate success  than  was  the  apparent  status  of  the  work  one  year  before. 
Recognition  of  this  fact  had  much  to  do  with  the  formulation  of  the 
policy  for  the  continuation  of  the  work  in  1911.  It  is  hoped  that  by 
putting  forth  an  especial  effort  the  small  amount  of  lost  ground  may 
be  regained,  and  that  by  1912  it  will  be  possible  to  state  with  assurance 
that  the  progress  hoped  for  at  the  close  of  1909  has  been  more  than 
equaled,  and  that  the  chances  are  still  favorable  to  the  successful 
outcome  of  the  work  and  to  the  establishment  of  an  efficient  and  auto- 
matic control  of  the  gipsy  moth  by  the  year  1916. 

It  should  be  understood  that  the  manuscript  of  this  bulletin  was 
completed  in  the  first  week  in  January,  1911,  and  that  no  more 
recent  developments  of  the  situation  have  been  considered  in  it, 
except  for  an  incidental  mention  of  the  progress  of  Apanteles 
lacteicolor. 


o 


UNIVERSITY  OF  FLORIDA 

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3  1262  09216  6361 


